World number two Novak Djokovic recovered from an ankle injury to reach the third round of the Shanghai Masters.
The Serb landed awkwardly after hitting a backhand in the second set of his match with Spain's Marcel Granollers and called for a medical timeout.
But after having his right ankle wrapped, Djokovic quickly hit his stride again and closed out a 6-2, 6-0 victory to set up a third round clash with Italy's Fabio Fognini.
Djokovic, who is looking to win his second tournament in a row after capturing last week's China Open in Beijing, played down the incident.
"It was just an awkward movement. I was in an off-balance position. I was running and I made a quick movement that caused a sharp pain at that instant moment," he said.
"But after the match we determined that it's nothing serious, so it's all fine."
New world number one Rafael Nadal enjoyed a safe passage to round three as he scored a routine win over Ukraine's Alexandr Dolgopolov.
Nadal went through 6-3, 6-2.
Sixth seed Juan Martin del Potro had to dig deep after overcoming a fever to beat Germany's Philipp Kohlschreiber.
Del Potro, who said he started feeling sick on Tuesday night, lost the first set 6-3 after being broken in his opening service game and then called for the trainer ahead of the second.
It looked bleak for the big Argentine at that stage but, relying on his big serve, he sent down 14 aces to power his way to victory.
He levelled the match by winning the second set 6-3 and, although Kohlschreiber broke at 6-5 down to stay in the match, Del Potro took the tie-break to set up a clash with Tommy Haas.
Roger Federer had an easy passage through to the last 16 as he overcame Andreas Seppi in straight sets.
Fifth seed Federer improved his record over the Italian to 10-0 with a 6-4, 6-3 victory.
In other matches, fourth seed Tomas Berdych beat Feliciano Lopez 7-6, 6-2 while seventh seed Jo-Wilfried Tsonga overcame Pablo Andujar 6-3, 6-2.