US Open

A fan yawns as he watches the match between Kei Nishikori, of Japan, and Milos Raonic, of Canada, during the fourth round of the 2014 U.S. Open tennis tournament Tuesday, Sept. 2, 2014, in New York. (AP Photo/Darron Cummings)

Darron Cummings/AP

A fan yawns as he watches the match between Kei Nishikori, of Japan, and Milos Raonic, of Canada, during the fourth round of the 2014 U.S. Open tennis tournament on Tuesday. 

Vinci of Italy serves to compatriot Giorgi at the U.S. Open tennis championships in New York...Roberta Vinci of Italy serves to compatriot Camila Giorgi at the U.S. Open tennis championships in New York September 2, 2013.

Kena Betancur/Reuters

Roberta Vinci of Italy serves during her straight sets win over compatriot Camila Giorgi at the US Open tennis championships in New York on Monday