Britain's Andy Murray returns the ball in the final of the French Open tennis tournament against Serbia's Novak Djokovic at the Roland Garros stadium in Paris.

Serbia's Novak Djokovic returns the ball in the final of the French Open tennis tournament against Britain's Andy Murray at the Roland Garros stadium in Paris.

Netherlands' Kiki Bertens reacts as she defeats Timea Bacsinszky of Switzerland during their quarterfinal match of the French Open tennis tournament at the Roland Garros stadium in...

Serbia's Novak Djokovic returns the ball in the fourth round match of the French Open tennis tournament against Spain’s Roberto Bautista Agut at the Roland Garros stadium in Pari...

Serena Williams of the U.S. serves the ball to Ukraine's Elina Svitolina during their fourth round match of the French Open tennis tournament at the Roland Garros stadium in Paris....

Canada's Milos Raonic returns the ball to Slovakia's Andrej Martin during their third round match of the French Open tennis tournament at the Roland Garros stadium in Paris.

Venus Williams of the U.S. waves after defeating compatriot Louisa Chirico during their second round match of the French Open tennis tournament at the Roland Garros stadium in Pari...

Novak Djokovic of Serbia holds his trophy aloft after defeating Andy Murray of Britain in the men's singles final at the Australian Open tennis championships in Melbourne, Australi...

Novak Djokovic of Serbia holds his trophy aloft after defeating Andy Murray of Britain in the men's singles final at the Australian Open tennis championships in Melbourne, Australi...

Novak Djokovic of Serbia celebrates after defeating Andy Murray of Britain in the men's singles final at the Australian Open tennis championships in Melbourne, Australia.

Flavia Pennetta, of Italy, reacts as she poses for photos with the championship trophy after beating Roberta Vinci, of Italy, in the women's championship match of the U.S. Open ten...

An American flag is displayed during a ceremony before the women's championship match of the U.S. Open tennis tournament in NEw York.

Serena Williams hugs Venus Williams after winning their quarterfinal match at the U.S. Open tennis tournament in New York, US.

Martina Hingis of Switzerland and Sania Mirza hold their trophies after winning the women's doubles final against Ekaterina Makarova of Russia and Elena Vesnina of Russia at the A...

Serena Williams of the United States holds up the trophy after winning the women's singles final against Garbine Muguruza of Spain, at the All England Lawn Tennis Championships in ...

Marin Cilic, of Croatia, reacts after defeating Kei Nishikori, of Japan, during the championship match of the 2014 U.S. Open tennis tournament, in New York. Cilic won his first Gra...

Serena Williams holds the U.S. Open tennis women's singles championship trophy during a visit to the 103rd floor of the Empire State Building, in New York. Williams defeated Caroli...

Marin Cilic, of Croatia, holds up the championship trophy after defeating Kei Nishikori, of Japan, in the championship match of the 2014 U.S. Open tennis tournament in New York.

Serena Williams, reacts after defeating Caroline Wozniacki, of Denmark 6-3, 6-3, during the championship match of the 2014 U.S. Open tennis tournament, in New York.

Serena Williams, reacts after defeating Caroline Wozniacki, of Denmark 6-3, 6-3, during the championship match of the 2014 U.S. Open tennis tournament, in New York.