OLYMPIC champion Andy Murray shrugged off shoulder trouble and the fatigue that followed his heroics in Rio to reach the third round of the Western & Southern Open.

On Sunday the Scot came through a gruelling four-set encounter with Juan Martin del Potro to win his second gold medal and barely three days later he was back on court, this time against another Argentinian, Juan Monaco, in Cincinnati.

Murray needed treatment on his shoulder during a tricky first set but soon recovered from the niggle to close out a 6-3 6-2 in one hour and 17 minutes.

"It's really humid here, quite different conditions to Rio," Murray told atpworldtour.com. "The court here is pretty fast. Rio was a lot slower than this. It took a bit of time to get into it, but I did all right.

"I did two short sessions yesterday and two short sessions today. I sometimes find that rather than doing one long session, if you're going into new conditions, it's a bit easier to do a couple of shorter sessions. I feel like I get my timing a bit quicker that way."

His next opponent will be South Africa's Kevin Anderson, who surprised 13th seed Richard Gasquet to win 6-2 6-4.