LONDON - Facing match point at 5-1 down in the third set, Rafael Nadal gave himself about a one-in-a-thousand chance of turning things around against Daniil Medvedev at the ATP Finals.

Those odds turned out to be more than good enough for the top-ranked Spaniard.

Nadal saved that match point with a perfect drop shot and then rallied to beat Medvedev 6-7(3), 6-3, 7-6(4) on Wednesday, keeping alive his chances of advancing from the group stage.

"Today is one of those days that one out of a thousand you win and it happened today," Nadal said.

"In that moment (facing match point), what you think is probably in five minutes you are in the locker room, because that's the more normal thing. In that moment, you play with not much pressure because you have almost lost."

Nadal looked headed for a second straight defeat at the season-ending tournament but won five games in a row to go 6-5 up in the decider. In the tiebreaker, Medvedev missed a routine forehand to hand Nadal a match point and then sent a backhand just wide. That shot was initially called in but was overturned by Hawk-Eye after Nadal challenged the decision.

The win gives Nadal a 1-1 record after two round-robin matches, while Medvedev fell to 0-2.

In the late match, Stefanos Tsitsipas beat defending champion Alexander Zverev 6-3, 6-2 for his second straight win, a result that guarantees him a place in the semifinals.

The other three players all still have a chance of advancing.

Tsitsipas, who is making his debut at the tournament for the world's top eight players after a breakthrough season, broke Zverev for a 5-3 lead in the first set and then twice more to go 5-1 up in the second.

With dozens of Greek flags being waved around London's O2 Arena, Tsitsipas then served out the match with an ace.

"Once again, it was not just me out there, but a whole bunch of excited people that came to support me," said Tsitsipas, the first Greek player to qualify for the event. "It was a crew situation."

Zverev could still advance with a win over Medvedev on Friday, and he also lost his second round-robin match last year on his way to the title.

"Things are still in my hands, and I'm looking forward to it, because I can still decide whether I'm here on Saturday or not," the German said. "There is nothing I can do about today now. He played a fantastic match, I thought. I played really bad."

Tsitsipas said he was playing with a pain-killing injection in his foot because of an injury but pledged to treat his match with Nadal as a must-win situation even though he's already through to the semifinals.

"I'm going to try to give my soul, and I think it's also a very good challenge for me in order to prepare for more difficult matches in the semifinals and the final potentially, so this match is going to give me a lot," he said. "It's going to educate me, and I'm going to try to get and absorb as much as I can from that."

In a rematch of this year's US Open final, Nadal came out looking much sharper than in his opening loss to Zverev and broke Medvedev twice in the second set.

But the Russian raced into a 4-0 lead in the third set and had two more break points in the next game. However, Nadal held and then saved a match point at 30-40 in his next service game with a backhand drop shot at the net.

Medvedev then started making more mistakes while Nadal played like a man with nothing to lose, going for winners all over the court.

"Rafa fought his best, because he could just say 'OK, it's over at 5-1 and just give me the point,' but we all know Rafa is not about this," Medvedev said. "I just need to close out such matches."

Nadal's preparations for the ATP Finals were hampered by an abdominal injury that forced him to pull out of the Paris Masters semifinals this month. But he insisted he feels fine physically, and is gradually finding his best game after an error-strewn performance against Zverev.

"I have been playing a better level of tennis than the first day in general terms," Nadal said. "Then to win this match is a combination of a lot of things: luck, some mistakes of Daniil, some good moments by myself at the end."

Nadal's win also strengthens his grip on the year-end No 1 ranking, as it means Novak Djokovic has to win the tournament to have any chance of overtaking him.

Djokovic had to beat Roger Federer on Thursday just to advance to the semifinals.

Associated Press