Alexander Zverev set up a last-four clash against Roger Federer in the ATP Finals after seeing off John Isner 7-6 (7/5), 6-3 on Friday while Novak Djokovic will take on Kevin Anderson.
Zverev played American giant Isner at London’s O2 Arena knowing a win by any scoreline would take him through to the semi-finals of the season-ending tournament.
The turning point in the round-robin match came at the end of the 12th game, when the 21-year-old German saved a set point on his own serve with an ace, going on to force a tie-break.
The players swapped mini breaks but Isner, 33, then faltered again on his own serve to hand the set to Zverev — meaning he no longer had any chance to qualify for the last four.
In the second set a single break of serve in the eighth game proved decisive and Zverev served out the match.
“It’s obviously great getting to the semi-finals,” he said. “But the tournament isn’t over. I am in the semi-finals. There’s only good opponents left. There’s only the best in the world.
“I’m playing Roger tomorrow, which is going to be a very difficult but hopefully very nice match. We’ll see how far I can go.”
Third seed Zverev, coached by Ivan Lendl, is the youngest semi-finalist at the ATP Finals since Juan Martin del Potro in 2009.
He has three titles under his belt this year, including the Madrid Masters, and now has more wins in 2018 than any other player, with 56, against 19 losses.
But although he is often talked about as the leader of the next generation, his record in Grand Slams is poor and he will be desperate to make a major statement in London.
“I am very, very disciplined,” he said. “I work hard. I like it because I know what I want, and I want to be the best. With any other attitude, you will not be.”
Second seed Federer, chasing his 100th title, beat Anderson in straight sets to top the Lleyton Hewitt Group on Thursday but both players progressed, meaning early exits for Kei Nishikori and Dominic Thiem.