Roger Federer, Serena Williams and Eugenie Bouchard among those in action at
Ana Ivanovic, of Serbia, serves against Alison Riske, of the United States, during the opening round of the 2014 U.S. Open tennis tournament, Tuesday, Aug. 26, 2014, in New York.Kathy Willens/The Associated Press
Alison Riske of the U.S. hits a return to Ana Ivanovich of Serbia during their match at the 2014 U.S. Open tennis tournament in New York, August 26, 2014.ADAM HUNGER/Reuters
Lauren Davis of the U.S. hits a return to Samantha Stosur of Australia during their match at the 2014 U.S. Open tennis tournament in New York, August 26, 2014.MIKE SEGAR/Reuters
Samantha Stosur of Australia serves to Lauren Davis of the U.S. during their match at the 2014 U.S. Open tennis tournament in New York, August 26, 2014.MIKE SEGAR/Reuters
Sam Querrey, of the United States, returns a serve against Maximo Gonzalez, of Argentina, during the first round of the 2014 U.S. Open tennis tournament, Tuesday, Aug. 26, 2014, in New York.Elise Amendola/The Associated Press
Maximo Gonzalez of Argentina hits a return between his legs to Sam Querrey of the U.S. during their match at the 2014 U.S. Open tennis tournament in New York, August 26, 2014.EDUARDO MUNOZ/Reuters
A ball person gathers game balls from the court during the first round of the 2014 U.S. Open tennis tournament, Tuesday, Aug. 26, 2014, in New York.Elise Amendola/The Associated Press
A tennis fan tries to get a photo of Kei Nishikori, of Japan, during a break in play against Wayne Odesnik, of the United States, during the first round of the 2014 U.S. Open tennis tournament, Tuesday, Aug. 26, 2014, in New York.Matt Rourke/The Associated Press
Pablo Andujar of Spain hits a return to Jack Sock of the U.S. during their match at the 2014 U.S. Open tennis tournament in New York, August 26, 2014.MIKE SEGAR/Reuters
John Isner, of the United States, follows through on a return against Marcos Giron, of the United States, during the opening round of the 2014 U.S. Open tennis tournament, Tuesday, Aug. 26, 2014, in New York.Kathy Willens/The Associated Press
Fabio Fognini, of Italy, selects game balls to serve against Andrey Golubev, of Kazakhstan, during the first round of the 2014 U.S. Open tennis tournament, Tuesday, Aug. 26, 2014, in New York.Frank Franklin II/The Associated Press
Fabio Fognini, of Italy, points to a spot on the court after a point against Andrey Golubev, of Kazakhstan, during the first round of the 2014 U.S. Open tennis tournament, Tuesday, Aug. 26, 2014, in New York.Frank Franklin II/The Associated Press
Jack Sock, of the United States, serves against Pablo Andujar, of Spain, during the first round of the 2014 U.S. Open tennis tournament, Tuesday, Aug. 26, 2014, in New York.Elise Amendola/The Associated Press
Victor Estrella Burgos, of Dominican Republic, returns a shot against Igor Sijsling, of the Netherlands, during the first round of the 2014 U.S. Open tennis tournament, Tuesday, Aug. 26, 2014, in New York.Darron Cummings/The Associated Press
Canada's Eugenie Bouchard serves to Olga Govortsova of Belarus during their match at the 2014 U.S. Open tennis tournament in New York, August 26, 2014.EDUARDO MUNOZ/Reuters
Canada's Eugenie Bouchard cools off during a break in play during her match against Olga Govortsova of Belarus at the 2014 U.S. Open tennis tournament in New York, August 26, 2014.EDUARDO MUNOZ/Reuters
Canada's Eugenie Bouchard is mobbed for autographs after defeating Olga Govortsova of Belarus during their match at the 2014 U.S. Open tennis tournament in New York, August 26, 2014.EDUARDO MUNOZ/Reuters
Petra Kvitova of the Czech Republic hits a return to Kristina Mladenovic of France during their match at the 2014 U.S. Open tennis tournament in New York, August 26, 2014.ADAM HUNGER/Reuters