Austria's Dominic Thiem returns the ball to Spain's Rafael Nadal during their second round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Thursday, May 29, 2014. (AP Photo/Darko Vojinovic)
Austria's Dominic Thiem returns the ball during the second round match of the French Open tennis tournament against Spain's Rafael Nadal at the Roland Garros stadium, in Paris, France, Thursday, May 29, 2014. (AP Photo/Darko Vojinovic)
Russia's Svetlana Kuznetsova celebrates winning her second round match of the French Open tennis tournament against Italy's Camilla Giorgi at the Roland Garros stadium, in Paris, France, Thursday, May 29, 2014. (AP Photo/Michel Spingler)
France's Gael Monfils returns the ball to Germany's Jan-Lennard Struff during their second round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Thursday, May 29, 2014. (AP Photo/Michel Euler)
France's Jo-Wilfried Tsonga returns the ball to Austria's Jurgen Melzer during the second round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Wednesday, May 28, 2014. (AP Photo/David Vincent)
Russia's Maria Sharapova serves the ball to Bulgaria's Tsvetana Pironkova during the second round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Wednesday, May 28, 2014. (AP Photo/David Vincent)
Taylor Townsend, of the U.S, returns the ball to France's Alize Cornet during their second round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Wednesday, May 28, 2014. (AP Photo/Darko Vojinovic)
Taylor Townsend, of the U.S, returns the ball to France's Alize Cornet during the second round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Wednesday, May 28, 2014. (AP Photo/Darko Vojinovic)
Germany's Andrea Petkovic returns the ball to Switzerland's Stefanie Voegele during their second round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Thursday, May 29, 2014. (AP Photo/David Vincent)
Germany's Andrea Petkovic returns the ball to Switzerland's Stefanie Voegele during their second round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Thursday, May 29, 2014. (AP Photo/David Vincent)
Serbia's Anna Ivanovic returns the ball during the second round match of the French Open tennis tournament against Ukraine's Elina Svitolina at the Roland Garros stadium, in Paris, France, Thursday, May 29, 2014. (AP Photo/Darko Vojinovic)
Serbia's Anna Ivanovic returns the ball during the second round match of the French Open tennis tournament against Ukraine's Elina Svitolina at the Roland Garros stadium, in Paris, France, Thursday, May 29, 2014. (AP Photo/Darko Vojinovic)
Serbia's Anna Ivanovic returns the ball during the second round match of the French Open tennis tournament against Ukraine's Elina Svitolina at the Roland Garros stadium, in Paris, France, Thursday, May 29, 2014. (AP Photo/Darko Vojinovic)
Serbia's Anna Ivanovic serves the ball during the second round match of the French Open tennis tournament against Ukraine's Elina Svitolina at the Roland Garros stadium, in Paris, France, Thursday, May 29, 2014. (AP Photo/Darko Vojinovic)