History-making Kei Nishikori was dumped out of the Shanghai Masters on Wednesday as Novak Djokovic cruised into the third round and defending champion Andy Murray was handed a walkover.
As the tournament came to life with the introduction of the big guns, America's Sam Querrey sent Nishikori tumbling 2-6, 6-1, 6-4 just days after his opponent became the first Japanese player to win the Japan Open.
Nishikori had treatment during the match on his right ankle, which he said had been bothering him since last week.
"I tried to play but he had a good serve," he said. "I broke him first in the third set but couldn't finish the match. It's disappointing but I was close to win with this injury. Nothing I can do," he said.
The 22-year-old Japanese romped into a 4-0 lead at the start of the match and sealed the opening set despite a medical timeout late in the set.
But a missed overhead early in the second set contributed to an early break for Querrey and the Japanese 14th seed lost his rhythm, showing his frustration as his rejuvenated opponent, ranked 22nd, levelled the match.
In the third set Nishikori secured an early break but Querrey won five straight games from 4-1 down to seal the match against the Japanese, at a career high of number 15 in the rankings after his weekend win over Canada's Milos Raonic, his first on the Tour since 2008.
Djokovic, who has a shot at regaining the world number one ranking if he wins the title and Federer loses before the quarter-finals, dismissed Bulgaria's Grigor Dimitrov 6-3, 6-2 in just 54 minutes.
"Very pleased with my serving in Beijing and obviously the first match today," said the second seed, who lost just five of his service points. "So that's something that I've been working on, obviously.
"Relying on the serve in today's tennis is a big advantage. So I try to get as many free points as possible. Today that was the case. It helped me a lot to defeat my opponent."
US Open champion Andy Murray did not even have to take to the court as Germany's Florian Mayer withdrew with a rib injury.
"I'll practise again. I mean, you never know whether it's a good or a bad thing. I mean, you're obviously prepared to play the match," said Murray.
"Yeah, sometimes it happens when you get a walkover. You just need to make sure you do enough practice and stay sharp."
Also in second-round action, there were wins for fourth seed Tomas Berdych of the Czech Republic, fifth-seeded Frenchman Jo-Wilfried Tsonga and 13th seed Stanislas Wawrinka of Switzerland.
But among the seeds to fall were Raonic and France's Gilles Simon.
Top seed Roger Federer, playing his first tournament on the Tour since a quarter-final defeat to Berdych at the US Open, was due to take on Taiwanese qualifier Lu Yen-hsun in an evening clash.
The Swiss world number one's build-up was clouded by a death threat from a blogger in China but the Internet user, in a fresh posting on the popular baidu.com site, said he had apologised. He remained at large.
A Shanghai police spokesman on Wednesday declined to comment on the case.
As the season draws towards to a close there are four places still up for grabs at next month's season-ending World Tour Finals in London. The top three have all qualified, along with the injured Rafael Nadal.