Jo-Wilfried Tsonga of France (Photo: Reuters)
Fourth-seeded Jo-Wilfried Tsonga defeated No. 13 Fernando Verdasco 7-6 (7), 6-2, after twice coming off for rain delays.
Benneteau, a former French Open quarterfinalist, gave the third-seeded Murray problems throughout a set in which both players were aggressive.
The Frenchman dictated many of the rallies, troubling Murray with some big forehands and driving him back with some stinging backhands.
But Benneteau, scampering to retrieve a shot from the baseline, slipped and rolled his right ankle. He also hurt his right wrist trying to break his fall.
''When he went down, he was making quite a lot of noise,'' Murray said. ''You see people turn their ankle, they make a lot of noise because the shock of it is quite scary.''
Benneteau received lengthy treatment and continued briefly before retiring.
Murray will face sixth-seeded Tomas Berdych of the Czech Republic, who recovered from a shaky first set to beat No. 12 Kei Nishikori of Japan 2-6, 6-2, 6-4.
Berdych has a 3-2 record against Murray, including a straight-sets win in the fourth round of the French Open two years ago.
''He plays a different style of tennis on the clay,'' Murray said. ''He has so much power, he's able to go through the court, hit pretty flat.''
Nishikori lost only two points on his serve in the first set and broke Berdych twice.
Murray, meanwhile, struggled to hold his opening service game and then broke Benneteau. But the Frenchman broke straight back when Murray, who had saved four break points, hit a forehand wide on the fifth.
On the same center court days ago, Argentine player Juan Monaco also turned his ankle in an almost identical way to Benneteau, and had to pull out of his match against Dutchman Robin Haase.
Later Thursday, seven-time defending champion Rafael Nadal was playing qualifier Mikhail Kukushkin of Kazakhstan, while top-ranked Novak Djokovic was to play No. 16 Alexandr Dolgopolov of Ukraine.
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