John Isner, of the US, serves to Spain's Tommy Robredo 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/David Vincent)
Switzerland's Roger Federer returns the ball to Russia's Dmitry Tursunov during the third round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Friday, May 30, 2014. (AP Photo/Darko Vojinovic)
Spain's Rafael Nadal returns during the third round match of the French Open tennis tournament against Argentina's Leonardo Mayer at the Roland Garros stadium, in Paris, France, Saturday, May 31, 2014. (AP Photo/Michel Euler)
France's Gael Monfils, right, and Italy's Fabio Fognini shake hands after their third round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Saturday, May 31, 2014. (AP Photo/David Vincent)
Italy's Fabio Fognini sits after falling as he plays France's Gael Monfils in their third round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Saturday, May 31, 2014. (AP Photo/David Vincent)
France's Gael Monfils returns the ball to Italy's Fabio Fognini during their third round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Saturday, May 31, 2014. (AP Photo/David Vincent)
France's Gael Monfils shouts after defeating Italy's Fabio Fognini in their third round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Saturday, May 31, 2014. (AP Photo/David Vincent)
Italy's Andreas Seppi returns the ball during the third round match of the French Open tennis tournament against Spain's David Ferrer at the Roland Garros stadium, in Paris, France, Saturday, May 31, 2014. (AP Photo/Darko Vojinovic)