Australian Open champion Stan Wawrinka crashed out of the Shanghai Masters with a second round loss to Gilles Simon on Wednesday, while Andy Murray advanced with an assured 7-5 6-2 win over Jerzy Janowicz.
With five spots still up for grabs at the season-ending ATP World Tour Finals, Wawrinka, who fell at the first hurdle in Tokyo last week, suffered the same fate in China with a 5-7 7-5 6-4 defeat to the Frenchman.
Wawrinka broke Simon's serve in the 12th game to claim the opening set but his 29th-ranked opponent battled back to tie the contest before overcoming an early break in the decider and emerging victorious after two and a half hours.
"Two weeks I didn't win matches," the Swiss said on the ATP's official website. "But you have to accept that and see what was the problem. I don't think I lost my game. I think I'm playing okay. I just had two really bad matches. I will take the positives from losing early."
American Jack Sock produced another upset when he defeated Japan's Kei Nishikori 7-6(5) 6-4. It was the American's first win over a top 10 opponent and brought Nishikori's hot streak to an end. The Japanese came into the tournament after wins in Kuala Lumpur and Tokyo.
Briton Murray made short work of an out-of-touch Janowicz to reach the third round with ease, blasting the big-hitting Pole off court in straight sets in less than 90 minutes.
The 27-year-old Scot, boosted by a win at the Shenzhen Open and reaching the semi-finals of the China Open over the last few weeks, is once again in contention for London after climbing to ninth in the Race.
Murray will next meet David Ferrer after the Spaniard survived a tense encounter against Martin Klizan, who served for the match in the second set, to progress.
The fifth seeded Spaniard found the going difficult against his Slovak opponent before grinding out a 4-6 7-6(4) 6-4 victory as he looks to climb up from his current 10th position in the race for the Tour Finals.
World number 553 Chuhan Wang's ATP World Tour debut was halted in another second round encounter when Tunisia's Malek Jaziri beat the Chinese wildcard, who had stunned 15th seed Fabio Fognini in the first round, 6-0 6-4.
The top three in ATP world rankings -- Novak Djokovic, Rafa Nadal and Roger Federer -- open their Shanghai Masters campaigns on Wednesday.
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