The top seeds compete at the U.S. Open
Action from Day 4 at Flushing Meadows
Agnieszka Radwanska of Poland serves to Carla Suarez Navarro of Spain during their women's singles match at the U.S. Open tennis tournament in New York August 30, 2012.JESSICA RINALDI/Reuters
Milos Raonic of Canada serves to Paul-Henri Mathieu of France during their men's singles match at the U.S. Open tennis tournament in New York August 30, 2012.RAY STUBBLEBINE/Reuters
Serbia's Ana Ivanovic returns a shot to Sweden's Sofia Arvidsson in the second round of play at the 2012 US Open tennis tournament, Thursday, Aug. 30, 2012, in New York.Mike Groll/The Associated Press
Tomas Berdych of the Czech Republic hits a return to Jurgen Zopp of Estonia during their men's singles match at the U.S. Open tennis tournament in New York August 30, 2012.KENA BETANCUR/Reuters
Dominika Cibulkova of Slovakia hits a return to Bojana Jovanovski of Serbia during their women's singles match at the U.S. Open tennis tournament in New York August 30, 2012.KENA BETANCUR/Reuters
Maria Kirilenko of Russia hits a return to Greta Arn of Hungary during their women's singles match at the U.S. Open tennis tournament in New York August 30, 2012.JESSICA RINALDI/Reuters
Jelena Jankovic of Serbia hits a return to Lara Arrubarrena-Vecino of Spain during their women's singles match at the U.S. Open tennis tournament in New York August 30, 2012.RAY STUBBLEBINE/Reuters
Kei Nishikori of Japan hits a return to Tim Smyczek of the U.S. during their men's singles match at the U.S. Open tennis tournament in New York August 30, 2012.KENA BETANCUR/Reuters
Roger Federer of Switzerland hits a return to Bjorn Phau of Germany during their match at the US Open men's singles tennis tournament in New York, August 30, 2012.ADAM HUNGER/Reuters
Agnieszka Radwanska of Poland hits a return to Carla Suarez Navarro of Spain during their women's singles match at the U.S. Open tennis tournament in New York August 30, 2012.JESSICA RINALDI/Reuters
Serbia's Jelena Jankovic serves to Spain's Lara Arruabarrena-Vecino in the second round of play at the 2012 US Open tennis tournament, Thursday, Aug. 30, 2012, in New York.Kathy Willens/The Associated Press
Angelique Kerber of Germany hits a return to Venus Williams of the U.S. during their match at the U.S. Open women's singles tennis tournament in New York, August 30, 2012.BILL KOSTROUN/Reuters
Roger Federer of Switzerland keeps his eyes on the ball as he sets to hit a return to Bjorn Phau of Germany during their match at the US Open men's singles tennis tournament in New York, August 30, 2012.ADAM HUNGER/Reuters
Sara Errani of Italy hits a return to Vera Dushevina of Russia during their match at the U.S. Open women's singles tennis tournament in New York August 30, 2012.BILL KOSTROUN/Reuters
Mardy Fish of the U.S. awaits a serve from Nikolay Davydenko of Russia during their men's singles match at the U.S. Open tennis tournament in New York August 30, 2012.EDUARDO MUNOZ/Reuters
Angelique Kerber of Germany wears multi-colored nail polish as she plays Venus Williams of the U.S. at the U.S. Open women's singles tennis tournament in New York, August 30, 2012.ADAM HUNGER/Reuters
Mardy Fish reacts after beating Russia's Nikolay Davydenko in the second round of play at the 2012 US Open tennis tournament, Thursday, Aug. 30, 2012, in New York.Darron Cummings/The Associated Press
France's Jo-Wilfried Tsonga reacts during his match against Slovakia's Martin Klizan in the second round of play at the 2012 US Open tennis tournament, Thursday, Aug. 30, 2012, in New York. Fifth-seeded Tsonga was upset by Klizan in the second round.Paul Bereswill/The Associated Press
Marin Cilic of Croatia celebrates after defeating Daniel Brands of Germany during their men's singles match at the U.S. Open tennis tournament in New York August 30, 2012.KENA BETANCUR/Reuters
Serena Williams of the U.S. reacts to a missed point against Maria Jose Martinez Sanchez of Spain during their women's singles match at the U.S. Open tennis tournament in New York August 30, 2012.EDUARDO MUNOZ/Reuters
Milos Raonic of Canada celebrates after defeating Paul Henri-Mathieu of France during their men's singles match at the U.S. Open tennis tournament in New York August 30, 2012.RAY STUBBLEBINE/Reuters
Nicolas Almagro of Spain reacts after defeating Philipp Petzschner of Germany during their men's singles match at the U.S. Open tennis tournament in New York August 30, 2012.JESSICA RINALDI/Reuters
Serena Williams (L) of the U.S. is congratulated by Maria Jose Martinez Sanchez of Spain after their women's singles match at the U.S. Open tennis tournament in New York August 30, 2012.EDUARDO MUNOZ/Reuters
Jo-Wilfried Tsonga of France leaves the court after his loss to Martin Klizman of Slovakia in their men's singles match at the U.S. Open tennis tournament in New York August 30, 2012.JESSICA RINALDI/Reuters
Maria Kirilenko of Russia signs autographs after defeating Greta Arn of Hungary in their women's singles match at the U.S. Open tennis tournament in New York August 30, 2012.JESSICA RINALDI/Reuters