MASON, Ohio (AP) - Novak Djokovic and Andy Murray won their opening matches at the Western & Southern Open in straight sets Wednesday, getting accustomed to the heat after spending the last two weeks in London and Canada.
Top-seeded Agnieszka Radwanska of Poland also advanced to the third round with a 6-4, 6-3 win over Sofia Arvidsson of Sweden.
Djokovic got the bronze medal at the Olympics in London, then won the Rogers Cup in Toronto on Sunday night. He was a little off in his opening set on a court baked in sunshine and 86-degree heat, then pulled away from Andreas Seppi of Italy 7-6 (4), 6-2.
Murray had the best moment of his career at Wimbledon, winning the Olympic gold on home soil. He had to withdraw from the Rogers Cup because of a sore knee, which he blamed on the transition from grass to hard courts.
Murray moved around the court well during his match against American Sam Querrey, taking control early in a 6-2, 6-4 win. Querrey repeatedly missed open shots while falling behind and managed only two break points during the match, both of which Murray saved.
Yaroslava Shvedova of Kazakhstan quit her match while trailing in the second set, overcome by the heat, and also dropped out of her later doubles match.
Radwanska, who received a first-round bye, felt a little rusty.
``The first match is always more difficult, with the different balls and conditions,'' she said. ``I was happy to get through it, especially since it was very hot. Hopefully, I'll better (Thursday).''
Radwanska, who lost to Serena Williams in the Wimbledon final and is ranked No. 3 in the world, will meet Sloane Stephens of the United States, who got into the tournament as a wild card.
"I'll just go out and play my game,'' Stephens said, adding with a smile, "I'm not going to tell you how I'm going to play, because she'll probably read this and know how to play.''
Eleventh-seeded Dominka Cibulkova withdrew with an injury after losing the first set in a tiebreaker against qualifier Andrea Hlavackova of the Czech Republic. China's Shuai Peng also advanced with a 6-3, 6-4 win over Roberta Vinci of Italy.
In men's action, No. 10-seeded Mardy Fish of the United States advanced to the third round by defeating Carlos Berlocq of Argentina 6-3, 6-1. Serbian Victor Troicki moved on to the third round with a 6-2, 6-0 win over Australian Lleyton Hewitt. Nikolay Davydenko of Russia beat Florian Meyer of Germany 6-3, 6-3.
Fish was happy to advance relatively easily against an unfamiliar opponent while still working back into form after a surgical procedure to correct a heart condition in May.
"It was nice to get on and off quickly, especially with a win,'' said Fish, who'd never played Berlocq in singles. "You also can get on and off quickly with a loss. It's somewhat tricky. You never know what to expect. I played as well today as I have all summer. He's a good player. If you're not on top of your game, you could be in trouble.''
AP freelance writer Mark Schmetzer contributed to this report.