With the No. 1 ATP Ranking on the line, Roger Federer will face one of the best big-match players on the ATP World Tour. The 36-year-old Swiss and Aussie Nick Kyrgios will meet for the third time in their FedEx ATP Head2Head series (1-1) on Saturday in the MercedesCup semi-finals in Stuttgart.

Kyrgios won their first matchup, saving two match points at the 2015 Mutua Madrid Open to beat Federer 6-7(2), 7-6(5), 7-6(12). The big-serving Aussie leaned on his first serve when in trouble and frustrated Federer by winning 83 per cent of those points.

At the time, Kyrgios was only 20 and just a year removed from stunning then-No. 1 Rafael Nadal at Wimbledon as the 144^th-ranked player.

But last year at the Miami Open presented by Itau, Kyrgios was a known threat, and Federer gained revenge in their electric semi-final played under the lights. The Aussie again erased two match points in the second set and belted an ace at 10/9 in the second-set tie-break to even the contest.

Watch The Best Moments From Kyrgios-Federer at 2017 Miami

But the Swiss didn’t let another opportunity go by, clinching the semi-final on his racquet 7-6(9), 6-7(9), 7-6(5). He’d complete his third Sunshine Double the next day.

“We’ve had some brutal matches against each other, in Miami, in Madrid,” Federer said after his straight-sets quarter-final win against Argentina’s Guido Pella on Friday. “He’s always dangerous, especially on the grass. I think I will enjoy playing against him.”

Read More: Relive Kyrgios-Federer From 2017 Miami

Both Federer and Kyrgios have impressed in Stuttgart during their returns to the ATP World Tour. Federer’s hiatus was self-imposed; the Swiss skipped the European clay-court swing for a second year in a row after falling in his Miami opener to Kyrgios’ countryman Thanasi Kokkinakis on 24 March.

But he’s dropped only one set while extending his grass-court win streak, dating back to 2017 Wimbledon, to 14 matches against German Mischa Zverev and Pella.

Kyrgios missed the past two months of singles play because of an injured right elbow, but the 23-year-old Aussie has shown few signs of any lingering problems. He beat German Maximilian Marterer, who made the fourth round at Roland Garros, and 2017 Fever-Tree Championships titlist Feliciano Lopez of Spain to make his second semi-final of the season (Brisbane).

Kyrgios and countryman Lleyton Hewitt are the only two players to beat Federer, Nadal and Novak Djokovic in their first meetings. Kyrgios is also 8-7 against players ranked inside the Top 4 of the ATP Rankings.

If Federer wins, he’ll overtake Rafael Nadal for the top ATP Ranking on Monday. The Swiss currently holds the record for most weeks at No. 1 (309). This is Federer’s only opportunity during the grass-court season to return to the top spot. He can’t improve his points tally at his next two events, the Gerry Weber Open in Halle and Wimbledon, where he won titles last year. Federer was last No. 1 during the week of 14 May.

Marton Fucsovics and Mischa Zverev had never played doubles together before arriving in Stuttgart this week for the MercedesCup. Nevertheless, they booked their place in the semi-finals with a 6-3, 5-7, 10-4 victory over Jonathan Eysseric and Lucas Pouille in 74 minutes on Friday.

The Hungarian-German team will now challenge Robert Lindstedt and Marcin Matkowski on Saturday. Fucsovics has never reached an ATP World Tour final in doubles, while Zverev has triumphed three times — twice with Mikhail Youzhny in 2008, and once last year with younger brother Alexander Zverev.

The winner of that semi-final will meet Philipp Petzschner and Tim Puetz in the final. The Germans advanced to the championship match by beating top seeds Aisam-Ul-Haq Qureshi and Jean-Julien Rojer 7-6(2), 6-3 in a big-serving 79-minute encounter.

Petzschner, the 2011 Stuttgart titlist (w/Melzer), will now compete to capture his eighth tour-level doubles crown (7-7 overall), while Puetz contests his first ATP World Tour final. Together they have teamed up to capture two ATP Challenger Tour crowns at Wroclaw in 2015 and Aix-en-Provence earlier this year.

The third seeds knocked out top seeds and defending champions Lukasz Kubot and Marcelo Melo, who needed to play two matches on Friday, 6-4, 6-7(3), 10-6 in 89 minutes. Earlier in the day, Kubot and Melo overcame Dutchmen Sander Arends and Matwe Middelkoop 4-6, 6-4, 10-8 in 81 minutes.

Inglot and Skugor will next meet second seeds Raven Klaasen and Michael Venus, who first beat Matthew Ebden and Malek Jaziri 2-6, 6-4, 10-4 in 70 minutes in the quarter-finals and then fourth seeds Divij Sharan and Artem Sitak 6-3, 6-2 in 52 minutes.

Inglot and Skugor will now look to add to the Gazprom Hungarian Open trophy (d. Middelkoop/Molteni) they won in April, while Klaasen and Venus triumphed at the Open 13 Provence (d. Daniell/Inglot) in February.

Roger Federer is now one win away from reclaiming the No. 1 ATP Ranking from Rafael Nadal.

The Swiss No. 1 seed defeated Argentine Guido Pella 6-4, 6-4 at the MercedesCup on Friday in his second match since 24 March. Federer needs to reach the final in Stuttgart to guarantee his third stint atop the rankings this season, trailing Nadal by just 100 points entering the week.

The 36-year-old has doubled his victory total in Stuttgart this week after arriving in Germany this year with a 2-2 record at the event. One year ago, Federer fell against then-World No. 302 Tommy Haas in his opening match. This year’s Australian Open and Rotterdam champion is attempting to win a grass-court trophy for the sixth consecutive year. With his triumph against Pella, Federer has won 14 consecutive matches on the mown lawns dating back to title runs at Halle and Wimbledon last year.

The Swiss showed his prowess on the surface, frequently swooping to net with swift aplomb against the left-handed Pella, who had not won a tour-level grass-court match (0-4) before this tournament. Federer lost just one point on serve in the first set, earning a break with a whipping inside-out forehand winner. He didn’t let slip the momentum, dancing on the grass to hit an inside-in forehand passing shot for an immediate break in the second set. 

The 17-time tour-level grass-court champion faced only one moment of difficulty, falling behind 15/40 while serving for the match at 5-4 in the second set. But Federer battled through with strong serving. He will next face talented Aussie Nick Kyrgios or 2017 Fever-Tree Championships winner Feliciano Lopez.

Did You Know?
Roger Federer got off to a career-best 17-0 start in 2018, before losing back-to-back matches in the Indian Wells final (l. to Del Potro) and his Miami opener (l. to Kokkinakis).