Top shots from U.S. Open

Rafael Nadal of Spain returns the ball against Ryan Harrison of the U.S. during their 2013 U.S. Open men's singles match at the USTA Billie Jean King National Tennis Center in Queens, N.Y., Aug. 26 , 2013.

Serena Williams returns a point to Italy's Francesca Schiavone during their women's singles match, Aug. 26 , 2013.

Tommy Robredo of Spain plays a forehand against Marinko Matosevic of Australia during their men's singles first round match, Aug. 26, 2013.

Serena Williams celebrates a point during her women's singles first round match against Francesca Schiavone of Italy on Day One of the 2013 U.S. Open, Aug. 26, 2013.

Roberta Vinci of Italy returns a shot to Timea Babos of Hungary during the first round of the 2013 U.S. Open tennis tournament, Aug. 27, 2013.

Fernando Verdasco of Spain can't reach a shot by Ivan Dodig of Croatia during the first round of the 2013 U.S. Open tennis tournament, Aug. 26, 2013.

Australia's Olivia Rogowska returns a shot to Sara Errani, of Italy, during the first round of the 2013 U.S. Open tennis tournament, Aug. 27, 2013.

Novak Djokovic, of Serbia, returns a shot to

Albert Ramos, of Spain, returns a shot to Australia's Bernard Tomic during the first round of the 2013 U.S. Open tennis tournament, Aug. 26, 2013.

Rafael Nadal, of Spain, serves to Ryan Harrison during the first round of the 2013 U.S. Open tennis tournament, Aug. 26, 2013.

Sam Querrey returns a shot to Guido Pella, of Argentina, during the first round of the 2013 U.S. Open tennis tournament, Aug. 27, 2013, in New York.

Michael Russell returns a shot against Richard Gasquet of France during the first round of the 2013 U.S. Open tennis tournament, Aug. 26, 2013.

Tomas Berdych of the Czech Republic returns a shot to Paolo Lorenzi, of Italy, during the first round of the 2013 U.S. Open tennis tournament, Aug. 27, 2013.

Milos Raonic, of Canada, returns a shot to Thomas Fabbiano, of Italy, during the first round of the 2013 U.S. Open tennis tournament, Aug. 27, 2013.

Agnieszka Radwanska, of Poland, returns a shot to Spain's Silvia Soler-Espinosa in the first round of the 2013 U.S. Open tennis tournament, Aug. 26, 2013.

Bernard Tomic, of Australia, returns a shot to Albert Ramos, of Spain, during the first round of the 2013 US Open tennis tournament, Aug. 26, 2013.

Victoria Duval, of the United States, leaps in celebration after defeating Samantha Stosur, of Australia, in the first round of the 2013 U.S. Open tennis tournament, Aug. 27, 2013.

Angelique Kerber, of Germany, returns a shot to

Sloane Stephens wipes her face during her match against Luxembourg's Mandy Minella in the first round of the 2013 U.S. Open tennis tournament, Aug. 26, 2013.

John Isner serves to Filippo Volandri, of Italy, during the first round of the 2013 U.S. Open tennis tournament, Aug. 27, 2013.

Rafael Nadal, of Spain, returns a shot to Ryan Harrison during the first round of the 2013 U.S. Open tennis tournament, Aug. 26, 2013.

Ivan Dodig of Croatia returns a shot against Fernando Verdasco of Spain during the first round of the 2013 U.S. Open tennis tournament, Aug. 26, 2013.

Caroline Wozniacki, of Denmark, casts a shadow as she serves to Ying-Ying Duan, of China, during the first round of the 2013 U.S. Open tennis tournament, Aug. 27, 2013.

Mona Barthel, of Germany, returns a shot to Johanna Larsson, of Sweden, during the first round of the 2013 U.S. Open tennis tournament, Aug. 27, 2013.

Caroline Wozniacki, of Denmark, casts a shadow as she serves to Ying-Ying Duan, of China, during the first round of the 2013 U.S. Open tennis tournament, Aug. 27, 2013.

Venus Williams prepares to serve to Belgium's Kirsten Flipkens during the first round of the 2013 U.S. Open tennis tournament, Aug. 26, 2013.

Venus Williams serves to Belgium's Kirsten Flipkens during the first round of the 2013 U.S. Open tennis tournament, Aug. 26, 2013.

Svetlana Kuznetsova, of Russia, follow through with a serve against Mallory Burdettte, of the United States, during the first round of the 2013 U.S. Open tennis tournament, Aug. 27, 2013.

Juan Monaco, of Argentina, returns a shot to Florian Mayer, of Germany, during the first round of the 2013 U.S. Open tennis tournament, Aug. 27, 2013.

Paul-Henri Mathieu, of France, serves to Tommy Haas, of Germany, during the first round of the 2013 U.S. Open tennis tournament, Aug. 27, 2013.

Fans shade themselves from the sun while watching a first round match at the 2013 U.S. Open tennis tournament, Aug. 27, 2013.

Camille Nickel of Salt Lake City jumps off the edge of a fountain for a photo outside Arthur Ashe Stadium on the first day of the 2013 U.S. Open tennis tournament, Aug. 26, 2013.