As Dominic Thiem and Rafael Nadal walked to the net, united in exhaustion and pain, their sweat-drenched shirts clung to their bodies. After four hours and 49 minutes of a five-set, instant classic night-match, which ended at 2:04 a.m. in a city that was already known for its all-nighters, there could only be one winner: Nadal, who offered a few words of consolation after all the running, hitting, sweating and battling. Their embrace over the net at the US Open, two months ago in New York City, remains one of the most evocative images of the year.

“It’s going to be stuck in my mind forever,” said Thiem, who will do well to store the ball-striking and industry from that day as an example of what’s possible this week at the Nitto ATP Finals, and also in the future. “I’m going to remember that match, for sure. Tennis is cruel sometimes.” Thiem’s hard-court performances at Flushing Meadows, against Kevin Anderson in the fourth round, and then against Nadal in the quarter-finals, were a major step in the right direction for a Top 10 player in transition.

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Having spent his childhood playing on red dirt, indoors or outdoors, Thiem has won eight of his 11 ATP World Tour titles on clay courts. Yet he has no intention of being categorised solely as a standout dirt-baller like his Austrian compatriot, former World No. 1 Thomas Muster, who won 40 of his 44 titles on clay.

The perennial goal of any elite tennis performer is to be consistent on every surface and Thiem, a member of the Top 10 in the ATP Rankings since June 2016, is no different. The word ‘improve’ is never far from the lips of Thiem or his long-time coach Gunter Bresnik. It’s a philosophy that has helped Thiem better his year-end position in the ATP Rankings in each of the past seven seasons, highlighted by a career-high of No. 4 shortly prior to last year’s Nitto ATP Finals.

Bresnik, who cut his teeth as a young coach to Boris Becker almost 30 years ago, said, “Every practice session has a purpose and we don’t focus on the ATP Rankings. The role of the coach is to encourage, help the player improve and realise his potential. If Dominic puts everything together he has the potential to be a Grand Slam champion.”

Thiem came close this season. With an ability to strike his backhand faster and with more spin on slower surfaces, he broke Nadal’s 50-match clay-court winning streak in the spring, en route to his second successive Mutua Madrid Open final (which he lost to Alexander Zverev), and once again performed strongly at Roland Garros, but fell to the Spaniard in his first Grand Slam final.

With the additional insight of Spain’s Galo Blanco in 2018, to complement Bresnik, Thiem’s performances are now on a higher plane, as is his approach to the sport. “As an elite performer, Dominic knows what he needs to do to play well, but he is also receptive to advice in order to improve and play well at every tournament he contests,” said Blanco.

By any standards, Thiem’s schedule remains relentless. For the second time in the past three seasons, the 25-year-old has broken the 50 match wins barrier, including an ATP World Tour-leading 30 victories on clay. He has contested more than 220 singles matches in the past three years, with a season-long total of 82 appearances in 2016, and 76 in 2017, and this year he will post another high number.

“Initially, I was completely exhausted, dealing with the jetlag, training and travel,” Thiem said of his globe-trotting. “But I got used to it quickly. I like to play matches, but now I [organise my] schedule better in order to play at my best level on every surface. It’s really, really tricky to go deep in every tournament you play, but that’s what I want to achieve.”

The confidence reaped two months ago at Flushing Meadows soon propelled Thiem to his first indoor hard-court title at September’s St. Petersburg Open. The triumph added to clay‑court trophies in 2018 at the Argentina Open in Buenos Aires and at the Open Parc Auvergne-Rhône-Alpes Lyon.

Yet Thiem was made to sweat on his Nitto ATP Finals qualification, the cherry on top of the cake for every player each season. In part due to injuries throughout the year, he didn’t secure his place for a third consecutive year until the final stretch of the season. He admitted, “I tried to block out the pressure and focused on winning matches. Although you always check out the results of the other guys in the ATP Race [To London], I felt fresher and was able to fight really hard because I had taken some time off during the year due to injuries.”

While he won’t have the luxury of time against his fellow elite performers at The O2 this week, something he traditionally needs early at tournaments to hit top form, Thiem will be hoping to add to his round-robin victories over Gael Monfils in 2016 and alternate Pablo Carreno Busta last year. “I’ve learned a lot in each of the past two years and it’s such a great event, with so many spectators and every session is sold out, which is absolutely amazing,” said Thiem, who has a 2-4 overall record at the season finale. “I’ve learned that I need to be 100 per cent from the very first ball. You don’t get any presents when you’re playing against the Top 8.

“I’ve had another great year and qualified for London, which remains a top priority at the start of each season. It means I’ve been really consistent, so I’m happy to be back again. I want to finish the year on a high and to take the lessons I’ve learned into 2019.”

It isn’t often that an edition of the Nitto ATP Finals is remembered for a semi-final, rather than what happened during the final. But that’s exactly what transpired in 2014.

That’s because there was no championship match that year. After claiming an epic semi-final victory over countryman Stan Wawrinka – a match for the ages – Roger Federer was forced to withdraw with a back injury ahead of a title bout with Novak Djokovic.

“We always give 100 per cent,” said Djokovic. “I’m sure that if he could’ve played, he would’ve done. So I wish him the best in his recovery. You cannot blame him. You never like to win, especially these big matches against big rivals, with a retirement. But that’s the way it is.”

Federer had little time to recover after a marathon two-hour and 48-minute affair against Wawrinka. A grueling primetime battle in London, it could go down as the greatest match ever played at The O2. The drama boiled over as Federer prevailed 4-6, 7-5, 7-6(6), with a bevy of momentum swings leaving fans falling out of their seats.

Wawrinka was in the midst of a breakout campaign, lifting his maiden Grand Slam trophy at the Australian Open and first ATP World Tour Masters 1000 crown in Monte-Carlo. Making his second appearance at the Nitto ATP Finals, he qualified for the semis after defeating Tomas Berdych and Marin Cilic. Federer, meanwhile, was bidding for a seventh crown at the season finale and boasted a 3-0 record in the group stage, including a 6-1, 6-0 blowout win over Andy Murray.

Something had to give when Federer and Wawrinka stepped on the court. The margins were razor thin throughout the match, with a spot in the championship on the line. After Wawrinka claimed the opening set, Federer responded in kind in the second, securing a break to love in the 12th game.

Wawrinka refused to back down as the third set got underway, breaking immediately and eventually serving for the match at 5-4. But Federer would have the last word, saving three match points in that game and eventually a fourth in the ensuing tie-break, before prevailing. Wawrinka attempted to serve-and-volley on all three of the match points on his racquet, with Federer passing him twice. A sublime drop volley would seal the win for the six-time champion, as the London faithful erupted in applause.

But, physically and emotionally exhausted, Federer would not be able to overcome the taxing encounter. He announced his withdrawal from the final just a few hours prior to the match on Sunday.

As for Djokovic… It’s certainly not the way he wanted to win, but the Serbian would depart London with the trophy for a third straight year. He dominated proceedings in the group stage, dropping a combined nine games prior to a three-set win over Kei Nishikori in the semis.

With the title, he joined an elite club in becoming the first player to win three straight Nitto ATP Finals crowns since Ivan Lendl from 1985-87. The only other player to achieve the feat was Ilie Nastase.

“I’m not one of those players that celebrates these particular wins, but I have to reflect on the whole season,” Djokovic added. “This trophy is definitely the crown for all the achievements that I had this year. I owe the credit to my team, to all the people who supported me all the way through, and plenty of joy. I’m very happy to be able to stand here and finish with this trophy.”

It capped an impressive campaign for the year-end No. 1, having also lifted trophies in Indian Wells, Miami, Rome, Wimbledon, Beijing and Paris.

Two players have already guaranteed their spot in the semi-finals of the Next Gen ATP Finals, but there will be a lot on the line on a pressure-packed final day of round-robin play on Thursday, with two spots in the last four still up for grabs.

One #NextGenATP contender who has already moved through is top seed Stefanos Tsitsipas. The Greek moved to 2-0 in Group A play on Wednesday, impressively dismissing 2018 Delray Beach Open champion Frances Tiafoe.

“I’m very satisfied with my performance. I was playing aggressive tennis, coming to the net, playing an all-around game, and being unpredictable, which helped a lot,” Tsitsipas said. “I used my forehand a lot, had a lot of winners from my forehand side. Just a great day at the office.”

Tsitsipas will have a chance to stay undefeated against Polish No. 1 Hubert Hurkacz. The two-time ATP Challenger Tour winner embraced the stage on Wednesday during his victory against Jaume Munar, a four-set battle. And he will hope to do the same against World No. 15 Tsitsipas.

“It’s great. Yeah, it’s amazing,” Hurkacz said of the atmosphere at the Next Gen ATP Finals. “Great people here supporting, loving tennis also. So it’s really fun to play here in front of this crowd.”

Second seed Alex de Minaur also booked a trip to the semi-finals after defeating last year’s runner-up, Andrey Rublev, in four sets. The Aussie was ecstatic to overcome an opponent with a weapon as massive as the Russian’s forehand, and De Minaur will face another powerful foe on Thursday in Taylor Fritz.

“The group of guys here, they all play some insanely good tennis and every match is going to be really tough, so I’m looking forward to going out there,” said De Minaur, the current leader of Group B. “Hopefully I can serve well and do a little bit of what I did today.”

Rublev is hoping to battle for a semi-final spot of his own, continuing his pursuit of a title at the Fiera Milano. The Russian will face Italian wild card Liam Caruana.

There are a variety of situations in which players can finish in the group stage. Only one player, Caruana, has been eliminated from semi-final contention. But he will surely battle in front of his home fans and try to spoil Rublev’s attempts at moving on.

SEMI-FINAL QUALIFICATION SCENARIOS
GROUP A 
1) Regardless of score, if S. TSITSIPAS defeats H. HURKACZ and F. TIAFOE defeats J. MUNAR, then S. TSITSIPAS wins the group and F. TIAFOE qualifies 2nd.
2) Regardless of score, if H. HURKACZ defeats S. TSITSIPAS and J. MUNAR defeats F. TIAFOE, then H. HURKACZ wins the group and S. TSITSIPAS qualifies 2nd.
3) If S. TSITSIPAS defeats H. HURKACZ in 3 or 4 sets and J. MUNAR defeats F. TIAFOE regardless of score, then S. TSITSIPAS wins the group and J. MUNAR qualifies 2nd.
4) If S. TSITSIPAS defeats H. HURKACZ in 5 sets and J. MUNAR defeats F. TIAFOE in 3 or 4 sets , then S. TSITSIPAS wins the group and J. MUNAR qualifies 2nd.
5) If S. TSITSIPAS defeats H. HURKACZ in 5 sets and J. MUNAR defeats F. TIAFOE in 5 sets, then S. TSITSIPAS wins the group and H. HURKACZ qualifies 2nd.
6) Regardless of score, if H. HURKACZ defeats S. TSITSIPAS and F. TIAFOE defeats J. MUNAR in 3 sets, then S. TSITSIPAS wins the group and F. TIAFOE qualifies 2nd.
7) If H. HURKACZ defeats S. TSITSIPAS in 4 or 5 sets and F. TIAFOE defeats J. MUNAR in 4 sets, then S. TSITSIPAS wins the group and F. TIAFOE qualifies 2nd.
8) If H. HURKACZ defeats S. TSITSIPAS in 3 sets and F. TIAFOE defeats J. MUNAR in 4 sets, then S. TSITSIPAS wins the group and H. HURKACZ qualifies 2nd.
9) If H. HURKACZ defeats S. TSITSIPAS in 3 sets and F. TIAFOE defeats J. MUNAR in 5 sets, then S. TSITSIPAS wins the group and H. HURKACZ qualifies 2nd.
10) If H. HURKACZ defeats S. TSITSIPAS in 4 sets and F. TIAFOE defeats J. MUNAR in 5 sets, then S. TSITSIPAS wins the group and H. HURKACZ qualifies 2nd.
11) If H. HURKACZ defeats S. TSITSIPAS in 5 sets and F. TIAFOE defeats J. MUNAR in 5 sets, then S. TSITSIPAS wins the group and F. TIAFOE qualifies 2nd.

GROUP B
1) Regardless of score, if A. DE MINAUR defeats T. FRITZ and A. RUBLEV defeats L. CARUANA, then A. DE MINAUR wins the group and A. RUBLEV qualifies 2nd.
2) Regardless of score, if T. FRITZ defeats A. DE MINAUR and L. CARUANA defeats A. RUBLEV, then T. FRITZ wins the group and A. DE MINAUR qualifies 2nd.
3) Regardless of score, if A. DE MINAUR defeats T. FRITZ and L. CARUANA defeats A. RUBLEV in 3 or 4 sets then A. DE MINAUR wins the group and T. FRITZ qualifies 2nd.
4) If A. DE MINAUR defeats T. FRITZ in 4 or 5 sets and L. CARUANA defeats A. RUBLEV in 5 sets, then A. DE MINAUR wins the group and T. FRITZ qualifies 2nd.
5) If A. DE MINAUR defeats T. FRITZ in 3 sets and L. CARUANA defeats A. RUBLEV in 5 sets, then A. DE MINAUR wins the group and A. RUBLEV qualifies 2nd.
6) If T. FRITZ defeats A. DE MINAUR in 3 sets and A. RUBLEV defeats L. CARUANA regardless of score, then T. FRITZ wins the group and A. DE MINAUR qualifies 2nd.
7) If T. FRITZ defeats A. DE MINAUR in 5 sets and A. RUBLEV defeats L. CARUANA in 3 sets, then A. DE MINAUR wins the group and A. RUBLEV qualifies 2nd.
8) If T. FRITZ defeats A. DE MINAUR in 4 or 5 sets and A. RUBLEV defeats L. CARUANA in 4 or 5 sets, then A. DE MINAUR wins the group and T. FRITZ qualifies 2nd.
9) If T. FRITZ defeats A. DE MINAUR in 4 sets and A. RUBLEV defeats L. CARUANA in 3 sets, then A. DE MINAUR wins the group and T. FRITZ qualifies 2nd.

Frances Tiafoe and Taylor Fritz have both had breakthrough seasons on the ATP World Tour in 2018, qualifying for the prestigious Next Gen ATP Finals. They are also on track to finish the year inside the Top 50 of the ATP Rankings for the first time. The last time two Americans aged 21 and under have done that came 15 years ago, when Andy Roddick, Mardy Fish and Tiafoe’s coach, Robby Ginepri, accomplished the feat.

That’s a massive achievement, and for more than the reason you’d expect.

“When I was 14, 15, if you would’ve asked me if Taylor would play tennis, I would not have believed it,” Tiafoe joked.

To an extent, even Fritz thought along the same lines. Tiafoe lost just three games against Fritz in a junior final in Tulsa, Oklahoma five years ago, after all. Fritz, the son of Kathy May Fritz, who reached the Top 10 in the world, went to regular high school in California at first.

“I always thought I was probably much better than I actually was when I was at that age, like, 14, 15 years old,” Fritz said.

Then he moved to Florida to train at a USTA facility. And that’s when he saw that there were players his age who could not only match him, but beat him.

“That’s when I realised that, wow, if I actually wanted to be a pro, I’m going to have to be better than those guys. And so I really went to work, and I had those guys to build off,” Fritz said. “I just worked really, really hard. And, they will all tell you Tommy [Paul], Reilly [Opelka], [Stefan] Kozlov, Frances, I wasn’t even close to being in the same league as those guys.

“It’s crazy, I guess, looking back now at where I am now and all the things I expect of myself now, and back then it seemed so far. All of this that I’m doing right now just seemed impossible.”

In a way, Tiafoe’s rise was not all that likely, either. The story has been told plenty — growing up in Maryland, Tiafoe spent much of his time at the Junior Tennis Champions Center in College Park, where his father was a janitor. He’d wander the facility as a young boy, watching players train while trying to understand their coach’s tips, then going to hit against the wall daily to try to learn the sport.

And now, Tiafoe is someone who other kids are looking up to. The 20-year-old became the youngest American ATP World Tour champion in more than a decade earlier this year at the Delray Beach Open.

Tiafoe’s coach, Ginepri, has been in his shoes, and in a sense, has been where his charge wants to be, climbing as high as No. 15 in the ATP Rankings and lifting three tour-level titles.

“It kind of comes back full circle in a way. I try to coach Frances with a lot of experiences from when I played, the do’s and the don’ts. But it’s just been a lot of fun working with him,” Ginepri said. “He comes every day with a smile on his face and works pretty hard, so he’s been improving. It’s been a great year for him. He’s the second-youngest after Andy [Roddick] to win his first title, in Delray. So it’s a good shadow to follow. He’s got a big upside career in front of him if he keeps putting in the work.”

And Ginepri also knows what it feels like to be moving towards the top of the game with other compatriots. Roddick finished that 2003 season World No. 1, and Fish would eventually reach the Top 10, too. They pushed each other to greater heights.

“Frances kind of pulled out in front of Taylor a little bit this year, but Taylor’s right behind,” Ginepri said of the pair, as the friends are now separated by just seven spots. “He’s had some injuries, some setbacks, but his game’s just as good as Frances’ so they’re going to be neck and neck and hopefully we’ll get a few more Americans up there.”

Last year, for instance, Jared Donaldson qualified for the Next Gen ATP Finals. There are currently eight Americans 23 and under inside the Top 200 of the ATP Rankings. And they’re all pushing each other forward.

And it hasn’t always been easy. Fritz, currently at a career-best World No. 47, climbed as high as No. 53 in 2016, when he was named the ATP Star of Tomorrow presented by Emirates. Injuries then slowed his progress and forced him outside the Top 100 before building back up again.

Fritz’s coach, David Nainkin, says that inevitably, friends know how one another is performing. And when one does well, the other sees that.

“It’s great to see Frances break out and win an [ATP World Tour] 250 in Delray,” Nainkin said. “They’re definitely great friends, but great rivals. They want to see each other do better, which will certainly push them.”

While Tiafoe is in Group A and Fritz is in Group B in Milan, both still have opportunities to reach the semi-finals, as they each hold a 1-1 record in round-robin play. And while the Americans hope to fly their flag high the rest of the week at the Fiera Milano, they know that there is still more to come for them in the future.

“Hopefully me and Taylor don’t get complacent,” Tiafoe said. “I think there’s way more me and him can do. I’m going to be pushing him.”

Alex de Minaur became the second player to guarantee his spot in the last four of the Next Gen ATP Finals on Wednesday, defeating 2017 finalist Andrey Rublev 4-1, 3-4(5), 4-1, 4-2.

“It was great. I knew coming in it was going to be a really tough match and I was going to have to play some really good tennis and not leave too many balls short because his forehand is seriously one of the most dangerous weapons out there on the Tour,” De Minaur said. “I’m really happy with my win. I thought I executed my gameplan really well and served really well.”

De Minaur came out swinging, losing just three service points in the first set. And despite a hiccup in the second-set tie-break, the Aussie was broken just once in the match, while he broke the Russian four times to earn a berth in the semi-finals.

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“It’s not over yet. Every match counts,” De Minaur said. “I’m very happy with my win today and it’s been a great year, but tomorrow’s another day and you’ve got to get back out there and keep doing the same.”

De Minaur, who is at a career-best No. 31 in the ATP Rankings, is the second seed here in Milan. And he will look to complete round-robin play undefeated on Thursday evening when he plays fourth seed Taylor Fritz. The pair has not faced off in a FedEx ATP Head2Head match, but De Minaur defeated Fritz earlier this year at an ATP Challenger Tour event in Surbiton.

While Rublev, the 2017 Umag champion, will be disappointed, he is 1-1 in Group B play. The fifth seed beat Fritz in a five-set thriller on Tuesday, and he will try to earn his second win at the Fiera Milano this year when he clashes against home favourite Liam Caruana.

Stefanos Tsitsipas came in as the favourite at the Next Gen ATP Finals, competing as the top seed. And the Greek showed why on Wednesday, beating third-seeded Frances Tiafoe 4-3((3), 4-3(5), 4-2 to become the first player to guarantee his spot in the Milan semi-finals.

“I never dropped my performance, I always stayed at 100 per cent almost, so [I am] very satisfied that I managed to stay calm and play every point like a match point,” Tsitsipas said. “Hopefully I can play like this in every match that I’ll be playing here at the Next Gen ATP Finals.”

One year ago, Tsitsipas was an alternate at this event. And after two impressive performances against strong Group A opponents, the 21-year-old knows he will have a chance to play for a spot in the championship match. But first, on Thursday, Tsitsipas will have an opportunity to go undefeated in round-robin play when he faces Polish No. 1 Hubert Hurkacz.

There will be plenty at stake in that duel, as undefeated champions at the Fiera Milano receive $407,000. Tsitsipas has never played Hurkacz in a professional match.

The Greek will be the favourite in that clash based off his performance against Tiafoe, this year’s Delray Beach Open champion. It was the pair’s first FedEx ATP Head2Head meeting, but Tsitsipas also defeated Tiafoe last year in Tokyo qualifying, winning that match in straight sets as well. The Greek won 78 per cent of his service points on Next Gen Arena, saving both break points he faced en route to a 70-minute victory.

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In the first two sets, there was nearly nothing between the two players. In fact, before the tie-breaks, Tiafoe had won more points than Tsitsipas. But the recent Intrum Stockholm Open titlist got out to early leads on both occasions and did well on his serve to keep Tiafoe from sneaking back into the match.

“I believe having a good start in a tie-break, having a lead with a mini-break, maybe, helps a lot. When you can just stay more focused and calm on what you’re doing — it’s tough when you’re close in the score — so I try to focus when I get a good lead at the beginning and be aggressive. That’s the most important thing.”

After the second set, Tiafoe utlised one of the tournament’s innovations, speaking to coach Robby Ginepri via their headsets. And his fellow American tried to encourage Tiafoe to sneak forward when possible and control play.

“Keep this guy on the run,” Ginepri said. ”It’s good level, [you’ve] just got to execute in the tie-breaks a little better. Hey, keep your swag out there, don’t get down. This is a long match right now. You’ve got it. Let’s go.”

But Tsitsipas’ offensive pressure proved too much, playing aggressively off the forehand wing. And after earning the only break of the match, the top seed held out for the triumph.