Roger Federer must wait until 2019 for another chance to reach 100 career titles after semi-final defeat by Alexander Zverev at the ATP Finals.

Zverev, 21, tipped by many as a future Grand Slam champion, triumphed 7-5 7-6 (7-5) at London’s O2 Arena.

On Sunday, he will face Novak Djokovic, who beat Kevin Anderson 6-2 6-2.

Zverev faced boos at the end of the match after he had – legitimately – stopped a point in the tie-break when a ball boy dropped a ball.

In scenes reminiscent of Naomi Osaka’s victory speech at the US Open when her win was overshadowed by Serena Williams’ outbursts, Zverev was left apologising to both the crowd and Federer after one of the biggest wins in his career.

“I apologised to Roger at the net already, he said it is OK and it is in the rules,” the world number five said.

“I’m sorry this happened. I didn’t mean to upset anybody.”

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‘The Pretender’ beats ‘the King’

Former Wimbledon champion Boris Becker, commentating for BBC TV, had said before the match between ‘the King and the Pretender’ that he believed Zverev was a future world number one.

With three Masters titles to his name, the young German has yet to make his mark on the Grand Slams – although his French Open quarter-final this year was a breakthrough.

But now he will get the chance to win the season-ending title, which is second only to the Slams in terms of prestige.

There were moments when Zverev seemed to show a bit too much respect for Federer.

His body shot at the Swiss in the sixth game of the first set was half-hearted and cost him a point, while he volleyed a ball that was well on its way out of the court in the next game – as if not quite believing that the great Federer was able to hit long.

But he oozed confidence when it mattered the most, setting up three set points on Federer’s serve in the 12th game.

Getting there had included a fantastic passing shot after he raced to Federer’s drop shot, and the roar that followed said it all.

He sealed the set when Federer hit a forehand wide and then kept the momentum going early in the second set when he immediately held to love.

The German was never going to get it all his own way, with Federer setting up three break points of his own with a stunning forehand on the line, and taking the game when Zverev could only get a racquet edge to the Swiss’ forehand.

But Zverev wasted no time in breaking back when a Federer forehand went wide and from then on they matched each other to set up the tie-break.

After setting up two match points, Zverev sealed victory on the second one with a fantastic backhand that Federer could not get anywhere near.

Why was Zverev booed?

Zverev should have been beaming after one of the biggest wins of his career, yet looked emotional and ended up feeling “lost” in his post-match interview after some Federer fans jeered.

Presumably they felt the German had showed gamesmanship when he stopped play in the tie-break after the ball boy came on to the court, although the rules state the point must be replayed in such circumstances.

Former British number one Annabel Croft, who was conducting the on-court interview, scolded the crowd for their negative reaction.

“He was playing by the rules so I think you all have to be a little more respectful,” she said.

BBC Sport presenter Sue Barker said she was “quite embarrassed” by the crowd’s reaction, while colleague Tim Henman called it “disappointing”.

“You have to play a let,” added former Wimbledon semi-finalist Henman. “Once Federer understood what had happened, he accepted it.”

Federer’s wait for 100th title continues

After Federer sealed his 99th career singles title in front of a home crowd in Basel last month, all eyes have been on when the great Swiss player will reach triple figures.

His chance to get there in Paris at the start of November was ended in the semi-finals by world number one Djokovic and in London he has once again fallen just short.

He did, however, get closer this week than looked likely after his poor – and grumpy – performance as he lost his opening round-robin match to Kei Nishikori.

Time is not on Federer’s side – with the Swiss having turned 37 in August – but the fact he won four titles this year, including his record-extending 20th Grand Slam title at the Australian Open, means few would bet against him reaching the milestone very soon.

Analysis

BBC tennis correspondent Russell Fuller

Winners having to apologise for winning is becoming a habit in 2018.

The atmosphere was not nearly as hostile as that faced by Naomi Osaka at the US Open, but Zverev was subjected to whistles and jeers by a significant minority of the crowd.

The decent majority, and the sure-footed intervention of interviewer Annabel Croft, helped salvage the situation.

Adulation can know no bounds, and it is by no means the first time devotion to Federer has overstepped the mark.

The match itself was a triumph for Zverev. He looked extremely assured throughout as he broke Federer to love to win the first set, and then held his nerve in the second set tiebreak.

The 21-year-old has won all four tie-breaks he has played this week.

Britain’s Jamie Murray and Brazilian partner Bruno Soares must continue their wait for an ATP Finals title after they lost to American pair Mike Bryan and Jack Sock in the semi-finals.

Murray and Soares were beaten 6-3 4-6 10-4 at London’s O2 Arena to go out at this stage for the third straight year.

Bryan and Sock only started playing together earlier this year when Bryan’s twin brother Bob was injured.

The fifth seeds will find out their final opponents later on Saturday.

French pair Pierre-Hugues Herbert and Nicolas Mahut face Colombians Juan Sebastian Cabal and Robert Farah at 18:00 GMT.

Sock reached the ATP Finals in the singles last year but, after dropping dramatically down the rankings, has found more success alongside 18-time Grand Slam champion Bryan.

“This is extremely special,” Sock said.

“My singles year wasn’t spectacular, there have been some low moments mentally, so to have success in doubles with a friend has been great.”

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Analysis

BBC tennis correspondent Russell Fuller

Mike Bryan and Jack Sock have proved themselves a formidable team since pairing up mid-season when Mike’s twin brother Bob needed hip surgery.

They have won both Wimbledon and the US Open. Mike has more Grand Slam men’s doubles titles than anyone in history, and Sock – who has had an awful year in singles – is an unpredictable and richly talented doubles player.

His forehand, packed with power and spin, made the difference in this match. Murray and Soares, despite the disappointment of a third successive semi-final defeat, may feel they could not have done much more.

Germany’s Alexander Zverev clinched the last spot in the ATP Finals semi-finals by beating John Isner, a result which ensured world number one Novak Djokovic finished top of their group.

Zverev nicked a first-set tie-break before breaking at the end of the second to win 7-6 (7-5) 6-3 in London.

Third seed Zverev will play Roger Federer in the semi-finals on Saturday.

Djokovic, who beat Marin Cilic 7-6 (9-7) 6-2 later on Friday, will play South Africa’s Kevin Anderson.

The 14-time Grand Slam champion is the heavy favourite to win the tournament after easing through the round-robin stage with three victories from his three matches.

In the doubles, Pierre-Hugues Herbert and Nicolas Mahut won their group by beating Mike Bryan and Jack Sock 6-2 6-2 in 53 minutes.

Bryan and Sock finished second and will face Britain’s Jamie Murray and Bruno Soares in the semi-finals.

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Djokovic provides another statement of intent

Djokovic was identified as the man to beat at the O2 following his remarkable rise back to the world number one ranking, with dominant performances against Isner and Zverev sending further warning signs to the rest of the field.

While he was made to work much harder by Cilic in the first set, the Serb produced another impeccable performance to maintain his record of not dropping a set this week.

Even though his passage to the semi-finals was already guaranteed as the group winner, Djokovic refused to let his intensity drop and strangled Cilic with a near-perfect service game.

The Wimbledon and US Open champion only dropped five points on serve in the match and won 100% of the points when he landed his first serve.

Croat Cilic only managed to win two receiving points in the first set, unable to puncture his opponent’s impenetrable serve once again at set point in the tie-breaker and paying the price when he buckled under pressure with a forehand into the net four points later.

Djokovic missed three break points in a lengthy opening game of the second set, then saw his 31-point winning streak on serve ended in the third game.

That only served to sharpen Djokovic’s focus, however, as he broke in the next game and again for a 5-2 lead before serving out to win in one hour and 36 minutes.

“Obviously I knew before the match that I had already qualified, and I knew who I’m playing, so it wasn’t easy to approach this match with 100% willingness to win it,” said Djokovic.

“But this is a unique format and both of us wanted to win from the first point. It was a close first set which probably decided the match.”

Zverev’s time to arrive on the big stage?

With the ‘big four’ of Federer, Djokovic, Rafael Nadal and Andy Murray all in their 30s, Zverev has long been identified as the young player most likely to fill the void when they retire.

The 21-year-old is yet to make a meaningful impact in the Grand Slams but, after adding eight-time major champion Ivan Lendl to his team, has reached the last four at the O2 for the first time.

Now, with Federer and possibly Djokovic standing in his way, back-to-back victories over the weekend would announce his arrival to a wider audience.

After showing mental resilience to edge past Cilic in his opening match, Zverev knew any victory against Isner would guarantee his place in the last four, despite being outclassed by Djokovic in his second.

As with the Cilic match, he delivered on the big points against the American to win a match in which there was little between the two players.

Isner out-served and knocked out

Zverev delivered an 143mph ace to wipe out a set point at 6-5 – the only break point of the first set – and went on to earn a hold which took the opener into a tie-break and ultimately proved pivotal.

Isner knew he had to win to stay in the tournament, with a two-set victory his only hope of reaching the semi-finals, but mistimed a forehand into the net on Zverev’s second set point.

The 6ft 10in American’s game is unsurprisingly built around his massive serve but he was outgunned by Zverev, who had a faster serve speed, higher first-serve percentage and more aces.

And, after Zverev took his first break point at 4-4 in the second, victory was quickly wrapped up with a hold to love and allowed him to start thinking about facing Federer.

“I’m unbelievably happy to be in the semi-finals,” Zverev said. “I’ve had such a good run over the last year.

“John was such a tough opponent and the last two matches could have gone either way for him. The first set was unbelievably tight. It’s always one or two points against him.

“I came up with some great shots in the tie-break as well and that helped because don’t want to be down with him serving for the set.”

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