Beijing - Rafael Nadal came from behind against hard-hitting Jack Sock on Friday to reach the China Open semi-finals and set up a rematch with his shock US Open conqueror Fabio Fognini.
The Spanish great, scrapping to recover his form after a tough year, was frequently outgunned by the American's howitzer forehand but he dug deep to see off the world No 30, 3-6, 6-4, 6-3.
"Yes, it was an important victory for me. Obviously I finished the match playing better than what I started. It's important because I came back," Nadal said.
"This year I lost a lot of matches when I had an advantage. So to have the chance to win a match when I start losing this one, so it's important for me, too.
Nadal had not reached a hardcourt semi-final for more than a year, but he will now play Fognini, who stunned him last month in the US Open third round, for a place in the title match.
"He's a great player. When you play against a great player, especially if you don't play to your best, your chances are lower," Nadal said of the Italian, who beat Uruguay's Pablo Cuevas 6-1, 2-6, 6-2.
"If I am able to play my best tomorrow... I am going to have my chances. If not, it's going to be tough. It's simple. Sport is simple."
On a cold, bright day, Nadal paid for a slow start when he was broken in the first game. Sock's big forehand kept Nadal under pressure throughout the set, which he ultimately yielded with a double-fault.
But the 14-time Grand Slam-winner hit back by breaking first-up in the second set, and he gave a fist-pump of relief and satisfaction when he eventually levelled the match 6-4.
They slugged it out to 3-3 in the third set until Sock blinked first, handing Nadal three break points, and for once the American's forehand misfired as he shanked a routine shot high into the stands.
And it was another miscued forehand which settled the quarter-final as Sock, serving to stay in it, hit one long to hand victory to Nadal on his first match point.
In the women's draw, Ana Ivanovic beat Anastasia Pavlyuchenkova 6-3, 7-5 to set up a semi-final with Timea Bacsinszky, who recovered from a first-set 'bagel' to beat Sara Errani 0-6, 6-3, 7-5.
Fourth seed Agnieszka Radwanska beat Angelique Kerber 6-1, 6-4 to reach the semi-finals, where she will play either Bethanie Mattek-Sands or Garbine Muguruza.
In the last men's quarter-final, unbeaten five-time champion Novak Djokovic is playing America's John Isner for the prize of a semi-final against David Ferrer, who beat Taiwan's Lu Yen-hsun 6-3, 6-1.
Collated results from the ATP/WTA China Open in Beijing on Friday (x denotes seeding):
Rafael Nadal (ESP x3) bt Jack Sock (USA) 3-6, 6-4, 6-3
Fabio Fognini (ITA) bt Pablo Cuevas (URU) 6-1, 2-6, 6-2
David Ferrer (ESP x4) bt Lu Yen-Hsun (TPE) 6-3, 6-1
Novak Djokovic (SRB x1) bt John Isner (USA x6) 6-2, 6-2
Agnieszka Radwanska (POL x4) bt Angelique Kerber (GER x10) 6-1, 6-4
Timea Bacsinszky (SUI x12) bt Sara Errani (ITA) 0-6, 6-3, 7-5
Ana Ivanovic (SRB x6) bt Anastasia Pavlyuchenkova (RUS) 6-3, 7-5
Garbine Muguruza (ESP x5) bt Bethanie Mattek-Sands (USA) 6-1, 7-5