Spain's Rafael Nadal earned a spot in the semifinals with a 6-4, 4-6, 6-2 win over defending champion Stefanos Tsitsipas of Green on Thursday in the Nitto ATP Finals in London.
In the other half of Group London 2020 play, Russia's Andrey Rublev picked up his first win of the tournament with a 6-2, 7-5 win over Austria's Dominic Thiem. Thiem had clinched the group's top seed, and a spot in the semifinals, on Tuesday with a win over Nadal.
Nadal (2-1 in the event) will face Russia's Daniil Medvedev in the semifinal round on Saturday in a rematch of the 2019 US Open final. Medvedev clinched his spot with an upset over World No. 1 Novak Djokovic on Wednesday.
Thiem (2-1) will play the runner-up finisher from the Group Tokyo 1970 on Saturday. The final semifinalist will be the winner of Friday's match in Group Tokyo 1970 between Djokovic and Germany's Alexander Zverev.
Nadal, with his win, moved into the semifinals of the event for the sixth time in his career, but he has yet to win it. The world's No. 2 ranked player needed two hours and five minutes to get by Tsitsipas; last year the pair battled for two hours and 52 minutes in the same spot. Nadal won that previous match, but did not advance out of round-robin play.
"Last year, I was a little bit unlucky not to be in the semifinals," Nadal said. "The year before I had to pull out. It is always difficult to play here against the best players in the world every single day (at the) end of the season. Most of the time, you get here a little bit tired, but this year is a little bit different."
Tsitsipas (1-2), 22, was vying to become the second-youngest player to defend his Nitto ATP Finals title. But four double faults didn't help his cause. Tsitsipas grinded through, and hung around by saving four of eight break points.
But Nadal hammered home 29 winners and advanced. He has won 71 straight matches after winning the first set.
"(To) be in the semi-finals here, in the last tournament of the year, is an important thing," Nadal said. "(I am) happy for that and I am looking forward to the semi-finals against Daniil (Medvedev)."
Rublev, meanwhile, won his first match of the tournament by sweeping Thiem -- who played with the knowledge he already had semifinal match in hand. Rublev (1-2) was eliminated from advancing on Tuesday.
"I feel happy to be here," said Rublev. "I was so close in my second match. I had match point and I was serving, so it could have been a completely different story if I won two matches. I would maybe still have a chance to be in the semi-finals ... It is a part of life."
It was Rublev's third straight win against Thiem. He set the tone throughout, and faced just one break point.
"I started really well, since the first point (and) since the first return," said Rublev. "Dominic didn't start that well and I took advantage (from) the beginning. That helped me to have more confidence and helped me to play better and better."
Rublev piled up more aces (11 to 10), more winners (26-16) and had just nine unforced errors compared to Thiem's 15.
Thiem, who upset Nadal on Tuesday, will face either Djokovic or Zverev in the semifinals. There was no time to worry about Thursday's result.
"Both of them are great," Thiem said. "Both are former champions of this tournament. The goal is to find the great intensity tomorrow in practice and then try to be 100 percent in the match on Saturday."
Play in Group Tokyo 1970 wraps up Friday with Djokovic vs. Zverev and Medvedev against Argentina's Diego Schwartzman. Schwartzman has been eliminated from advancing.
--Field Level Media