UPDATE 1-Tennis-Nadal outlasts Tsitsipas, must wait for semi-final spot

For the second time in three days the indomitable Rafael Nadal fought off one of the game's rising powers, outlasting swashbuckling Greek Stefanos Tsitsipas 6-7(4) 6-4 7-5 to stay alive at the ATP Finals on Friday. However, the 33-year-old Spaniard will not know until later on Friday whether his Herculean effort was in vain.

His second round-robin victory meant Daniil Medvedev can no longer progress but Nadal needs the Russian to do him a favour and beat Alexander Zverev in the evening singles if he is to secure a semi-final spot from a complex group. Should that happen, Nadal would actually top the standings and face six-time champion Roger Federer in Saturday's semis.

If defending champion Zverev, who beat an off-key Nadal on Monday, prevails, then the Spaniard will finish third in the group and be eliminated. Whatever the outcome of the later match, 19-time Grand Slam champion Nadal showed just why he will complete the year ranked world number one for the fifth time.

After losing a tight opening set he raised his level, unleashing a ferocious onslaught that his 21-year-old Greek opponent met head on but finally could not withstand. Afternoon sessions at the 17,500-seat O2 Arena can sometimes be a little flat but Nadal, roaring his trademark "Vamos" and upper-cutting the air after crucial points, whipped the crowd to a frenzy. Tsitsipas responded in similar fashion in a classic scrap.

Nadal is the oldest player to finish a year ranked number one since ATP rankings began in 1973 and he was presented with a huge trophy on court afterwards. "Honestly, what can I say? I am super happy," Nadal told the crowd. "After all the things that I went through in my career in terms of injuries, I never thought at the age of 33 and a half that I will have this trophy in my hands again."

Tsitsipas was already guaranteed his semi-final place but, to his immense credit, stood toe-to-toe for nearly three hours with the game's ultimate warrior. Quite what effect that will have on his energy levels for the weekend, when he could even face Nadal in the final, is unclear. But his attitude was admirable.

There was nothing between the players in the opening set with not a break point in sight. Tsitsipas was quite happy to slug it out from the baseline and earned two set points in the tiebreaker with a barrage of forehands that even Nadal could not contain. He then banged down an ace to take the opening set.

Nadal beat Medvedev in his previous match from 1-5 down in the decider -- a victory for sheer bloody-mindedness. This time it was his superlative play that turned the match. Tsitsipas, who had not dropped a set so far, began to feel the pace and saved break points at 2-2 and 3-3 but Nadal was now in hunting mode and at 4-4 he finally cornered his prey to break for the first time.

A long bathroom break seemed to revive Tsitsipas and he kept his nose ahead in a high-quality decider. Nadal nervelessly held serve at 4-5, then broke in the next game when Tsitsipas, in at the net, could not control a low volley.

Nadal wrapped it up in the next game before settling back to await his fate later.

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