Defending champion and Olympic gold medalist Andy Murray was a third-round upset victim Thursday at the $2.825 million Western & Southern Open, the seventh of nine ATP Masters events this year.

French lucky-loser Jeremy Chardy knocked out the third-seeded Murray 6-4, 6-4 on the hardcourts at the Lindner Family Tennis Center. The British star was riding an eight-match winning streak heading into Thursday.

Murray titled here in 2008 and last year, beating Novak Djokovic in both finals in suburban Cincinnati.

Meanwhile, sixth-seeded Juan Martin del Potro got past Serb Viktor Troicki 7-6 (7-2), 2-6, 6-1 and 10th-seeded American Mardy Fish handled Czech veteran Radek Stepanek 6-3, 6-3. The former U.S. Open champion del Potro was a bronze medalist at the London Summer Games two weeks ago. Fish is a two-time Cincinnati runner-up.

Up next for del Potro will be Chardy.