Milos Raonic, Serena Williams and Eugenie Bouchard take to the court in New York
Eugenie Bouchard, of Canada, returns a shot to Sorana Cirstea, of Romania, during the second round of the 2014 U.S. Open tennis tournament Thursday, Aug. 28, 2014, in New York.Darron Cummings/The Associated Press
Milos Raonic of Canada serves to Peter Gojowczyk of Germany during their match at the 2014 U.S. Open tennis tournament in New York, August 28, 2014.MIKE SEGAR/Reuters
Victoria Azarenka, of Belarus, returns a shot to Christina McHale, of the United States, during the second round of the 2014 U.S. Open tennis tournament, Thursday, Aug. 28, 2014, in New York.Elise Amendola/The Associated Press
Ana Ivanovic, of Serbia, returns a shot against Kirolina Pliskova, of the Czech Republic, during the second round of the 2014 U.S. Open tennis tournament, Thursday, Aug. 28, 2014, in New York.Frank Franklin II/The Associated Press
Qiang Wang, of China, returns a shot against Casey Dellacqua, of Australia, during the second round of the 2014 U.S. Open tennis tournament, Thursday, Aug. 28, 2014, in New York.Kathy Willens/The Associated Press
Karolina Pliskova of the Czech Republic serves to Ana Ivanovic of Serbia during their match at the 2014 U.S. Open tennis tournament in New York, August 28, 2014.ADAM HUNGER/Reuters
Pablo Andujar, of Spain, returns a shot to Kei Nishikori, of Japan, during the second round of the 2014 U.S. Open tennis tournament, Thursday, Aug. 28, 2014, in New York.Matt Rourke/The Associated Press
Guillermo Garcia-Lopez, of Spain, tries to return a shot Sam Querrey, of the United States, against during the second round of the 2014 U.S. Open tennis tournament, Thursday, Aug. 28, 2014, in New York.Kathy Willens/The Associated Press
Jan-Lennard Struff, of Germany, returns a shot to John Isner, of the United States, during the second round of the 2014 U.S. Open tennis tournament, Thursday, Aug. 28, 2014, in New York.Frank Franklin II/The Associated Press
Fans watch from a walkway at the top of Grandstand as Jo-Wilifried Tsonga, of France, serves against Aleksandr Nedovyesov, of Kazakhstan, during the second round of the 2014 U.S. Open tennis tournament, Thursday, Aug. 28, 2014, in New York.Matt Rourke/The Associated Press
Serena Williams, of the United States, follows through as she returns a shot during the second round of the 2014 U.S. Open tennis tournament, Thursday, Aug. 28, 2014, in New York.Elise Amendola/The Associated Press
John Isner of the U.S. serves to Jan-Lennard Struff of Germany during their match at the 2014 U.S. Open tennis tournament in New York, August 28, 2014.ADAM HUNGER/Reuters
Serena Williams of the U.S. serves to compatriot Vania King at the 2014 U.S. Open tennis tournament in New York, August 28, 2014.MIKE SEGAR/Reuters
Monica Niculescu, of Romania, returns a shot against Barbora Zahlavova Strycova, of the Czech Republic, during the second round of the 2014 U.S. Open tennis tournament, Thursday, Aug. 28, 2014, in New York.Kathy Willens/The Associated Press
Nicole Gibbs, of the United States, returns a shot to Anastasia Pavlyuchenkova, of Russia, during the second round of the 2014 U.S. Open tennis tournament, Thursday, Aug. 28, 2014, in New York.Kathy Willens/The Associated Press
A line judge motions to the chair umpire after ducking a serve from Novak Djokovic, of Serbia, against Paul-Henri Mathieu, of France, during the second round of the 2014 U.S. Open tennis tournament, Thursday, Aug. 28, 2014, in New York.Elise Amendola/The Associated Press
Jo-Wilfried Tsonga of France serves to Aleksandr Nedovyesov of Kazakhstan during their match at the 2014 U.S. Open tennis tournament in New York, August 28, 2014.ADAM HUNGER/Reuters
Novak Djokovic of Serbia hits a return to Paul-Henri Mathieu of France during their match at the 2014 U.S. Open tennis tournament in New York, August 28, 2014.MIKE SEGAR/Reuters