Nadal exits, but stays on top of the world

London : Rafael Nadal was unable to crown his season with a first ATP Finals title but he ends it as world number one and with a chance to lead Spain to Davis Cup glory.

The Spaniard, who came to London under an injury cloud, had a terrible start to his week at the O2 Arena, crushed in straight sets by defending champion Alexander Zverev in his first round-robin match.

But he produced a performance of astonishing grit to recover from 5-1 and match point down against Daniil Medvedev and saw off Stefanos Tsitsipas in three sets on Friday.

It was not quite enough to reach the semi-finals but Nadal leaves London after securing the year-end number one ranking for a fifth time, pulling level with Roger Federer and Novak Djokovic.

Nadal was in the strange position after his win against 21-year-old Tsitsipas of not knowing whether he would be heading home or playing Federer in the knockouts.

Later, Zverev's win against Medvedev confirmed his tournament was over. The 33-year-old, who was presented with the trophy for securing the number spot on court, said it was difficult to compare the achievement with winning a Grand Slam.

Nadal is now on 19 majors, just one behind Federer after winning his 12th French Open this year and his fourth US Open crown.

"I know it is something so important because to achieve this you have to play well for 11 months," he said. "To win a Grand Slam you have to play well two weeks.

But it's difficult to compare. For me personally, when you win a Grand Slam, you win a Grand Slam winning the last point, and that feeling you, can't have it here. That's the big difference."

But he said finishing on top of the world was a great achievement after his struggles with injuries earlier in the season.

And he was delighted to pull level on five year-end finishes with Djokovic and Federer -- the other two members of the "Big Three".