Latvia's Ernests Gulbis returns the ball during the third round match of the French Open tennis tournament against Radek Stepanek of the Czech Republic at the Roland Garros stadium, in Paris, France, Friday, May 30, 2014. (AP Photo/David Vincent)
Latvia's Ernests Gulbis returns the ball during the third round match of the French Open tennis tournament against Radek Stepanek of the Czech Republic at the Roland Garros stadium, in Paris, France, Friday, May 30, 2014. (AP Photo/David Vincent)
Croatia's Marin Cilic returns the ball during the third round match of the French Open tennis tournament against Serbia's Novak Djokovic at the Roland Garros stadium, in Paris, France, Friday, May 30, 2014. (AP Photo/David Vincent)
Serbia's Novak Djokovic returns the ball during the third round match of the French Open tennis tournament against Croatia's Marin Cilic at the Roland Garros stadium, in Paris, France, Friday, May 30, 2014. (AP Photo/David Vincent)
Serbia's Novak Djokovic returns the ball to Croatia's Marin Cilic during their third round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Friday, May 30, 2014. (AP Photo/Michel Spingler)