Nadal digs deep to beat Medvedev in London

Following that match, Stefanos Tsitsipas's straight-sets win over defending champion Alexander Zverev left Nadal, Medvedev and Zverev fighting for one spot in the semi-finals.

The 33-year-old Nadal looked beaten on Wednesday as 23-year-old debutant Medvedev broke serve twice in the decider to stand on the brink of a first career victory over the Spaniard, who he pushed to five sets in an epic US Open final in September.

For once, world No.1 Nadal's trademark fighting spirit seemed to have deserted him but he saved a match point at 1-5 with a superb drop shot and was suddenly re-energised.

Twice Medvedev served for the match, at 5-2 and 5-4, but he tightened up and Nadal, roared on by the 02 Arena crowd, needed no second invitation to take advantage.

"Today is one of those days that one out of 1,000 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 are almost lost."

For Medvedev, he knew it was never going to be an easy result.

"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."

Later on Wednesday, debutant Tsitsipas crushed defending champion Alexander Zverev 6-3 6-2 to book his place in the last four with a match to spare.

The 21-year-old, the first Greek player to qualify for the elite eight-man season-ender, backed up his opening win over Medvedev with a virtuoso performance.

The Greek broke in the eighth game when Zverev opted to serve and volley on a second serve but made a mess of a low volley and from that point on it was one-way traffic.

Zverev's level tailed off alarmingly in the second set and Tsitsipas wrapped things up with an ace.

Australian Associated Press