Olympic champion Murray moves into last 16 at Toronto

By Frank Pingue

TORONTO (Reuters) - Andy Murray battled some pain but showed no signs of an Olympic hangover as the gold medalist moved into the last 16 of the Toronto Masters, while a fatigued Juan Martin del Potro was one of five seeds ousted on Wednesday.

Murray, playing his first match since his triumph at the London Games on Sunday, called out a trainer late in a 6-1 6-3 win over Italian Flavio Cipolla, which he later attributed to a change of playing surfaces from grass to a hard court.

"I feel on the grass courts the muscles get tired but the joints not so much, but on the hard courts the knees, ankles and hips take quite a fair pounding," Murray, whose match was his first on a hard court since early March, told reporters.

"And because I haven't had enough days to adjust to the surface that's probably why there were a few aches and pains."

The Briton, who appeared to hurt himself while chasing down a forehand, occasionally rubbed his left knee and had about five minutes of massage on his left quadriceps while leading the final set 3-2.

Still, the second seed, who is scheduled to face big-serving Canadian Milos Raonic in the third round, managed to chase down drop shots and held his serve throughout the 82-minute match.

Defending champion Novak Djokovic cruised to a 6-2 6-3 win over Australian Bernard Tomic in 71 minutes, setting up a third-round match with American Sam Querrey, who upset 13th seed Kei Nishikori of Japan 6-2 6-3.

Third seed Frenchman Jo-Wilfried Tsonga was the highest seeded player eliminated on Wednesday, falling 6-4 7-6 to compatriot Jeremy Chardy.