Rafael Nadal battled back from the brink of defeat to beat Italian Fabio Fognini and reach the semi-finals of the China Open.
The Spaniard was a set and 4-1 down, but recovered to win 2-6 6-4 6-1 and extend his unbeaten run to 20 matches.
Nadal, 27, will regain the world number one ranking if he beats fourth seed Tomas Berdych in the semi-finals.
Current world number one Novak Djokovic will play French fifth seed Richard Gasquet in the other semi.
Djokovic, the defending champion, swept past American Sam Querrey 6-1 6-2, while Gasquet defeated Spanish fifth seed David Ferrer 6-3 6-4 and Berdych beat eighth seed John Isner of the US 7-5 6-2.
A return to the number one ranking for the first time since July 2011 was looking unlikely for Nadal after he lost the first set against Fognini and was just a point away from trailing 5-1 in the second.
But the Mallorca-born left-hander - who looked to be struggling with his knee at one point - rediscovered his form, relinquishing just one more game to the world number 19 on his way into the final four.
Nadal is enjoying one of his best years despite missing the Australian Open with a knee injury, and he remains unbeaten on hard courts in 2013 having
On the possibility of replacing Djokovic as world number one, he said: "It's something that doesn't create more pressure for me.
"It's something that already happened in the past. If that happens again, it will be good, it will be special for me."
"It is not the moment to think about number one, it is the moment to think about Berdych or Isner."
Meanwhile, in the women's tournament, world number one Serena Williams powered past sixth seed Caroline Wozniacki 6-1 6-4.
The Dane offered brief resistance to break Williams's serve in the sixth game of the second set before the 32-year-old American went on the offensive in a 38-shot rally in the seventh.
Williams, winner of 17 Grand Slam singles titles, extinguished any hope of a comeback to book a semi-final meeting with Poland's third seed Agnieszka Radwanska, who beat Angelique Kerber of Germany 7-6 (9-7) 6-4.
"I felt I played really well tonight, especially in the first set," said Williams.
"I played well in the second set too, but I think Caroline just played so much better and she lifted her game so much.
"But I think overall it was the best performance I've had this week, which I'm excited about."
There was disappointment for home favourite Li Na, who was beaten 4-6 6-2 6-4 by 2011 Wimbledon champion Petra Kvitova.
The Czech left-hander will face Serb Jelena Jankovic, a 6-7 6-4 6-4 winner over Lucie Safarova, in the last four.