Best of Wimbledon

Serena Williams of the U.S. reacts after missing a point during her match against Timea Babos of Hungary at the Wimbledon Tennis Championships in London, July 1, 2015. REUTERS/Toby Melville

Kei Nishikori of Japan (L) waits to recieve a serve during his match against Simone Bolelli of Italy at the Wimbledon Tennis Championships in London, June 29, 2015. REUTERS/Toby Melville

Heather Watson of Britain keeps her eye on the ball during her match against Daniela Hantuchova of Slovakia at the Wimbledon Tennis Championships in London, July 1, 2015. REUTERS/Suzanne Plunkett

Caroline Wozniacki of Denmark hits a shot during her match against Denisa Allertova of the Czech Republic at the Wimbledon Tennis Championships in London, July 2, 2015. REUTERS/Toby Melville

Caroline Wozniacki of Denmark serves during her match against Saisai Zheng of China at the Wimbledon Tennis Championships in London, June 30, 2015. REUTERS/Toby Melville

Nick Kyrgios of Australia holds his necklace in his mouth during his match against Juan Monaco of Argentina at the Wimbledon Tennis Championships in London, July 1, 2015. REUTERS/Stefan Wermuth

Caroline Wozniacki of Denmark serves during her match against Saisai Zheng of China at the Wimbledon Tennis Championships in London, June 30, 2015. REUTERS/Henry Browne

Roger Federer of Switzerland hits a shot during his match against Sam Querrey of the U.S. at the Wimbledon Tennis Championships in London, July 2, 2015. REUTERS/Stefan Wermuth

Grigor Dimitrov of Bulgaria plays a shot through his legs during his match against Federico Delbonis of Argentina at the Wimbledon Tennis Championships in London, June 29, 2015. REUTERS/Toby Melville

A Ball boy gives Joao Sousa of Portugal his racket back during his match against Stan Wawrinka of Switzerland at the Wimbledon Tennis Championships in London, June 29, 2015. REUTERS/Suzanne Plunkett

Kei Nishikori of Japan reacts after winning his match against Simone Bolelli of Italy at the Wimbledon Tennis Championships in London, June 29, 2015. REUTERS/Toby Melville

Victoria Azarenka of Belarus hits a shot during her match against Kirsten Flipkens of Belgium at the Wimbledon Tennis Championships in London, July 1, 2015. REUTERS/Stefan Wermuth

Dustin Brown of Germany celebrates after winning his match against Rafael Nadal of Spain at the Wimbledon Tennis Championships in London, July 2, 2015. REUTERS/Stefan Wermuth

Rafael Nadal of Spain hits a shot during his match against Dustin Brown of Germany at the Wimbledon Tennis Championships in London, July 2, 2015. REUTERS/Stefan Wermuth

Jo-Wilfried Tsonga of France slips during his match against Albert Ramos-Vinolas of Spain at the Wimbledon Tennis Championships in London, July 2, 2015. REUTERS/Henry Browne

Milos Raonic of Canada hits a shot during his match against Tommy Haas of Germany at the Wimbledon Tennis Championships in London, July 1, 2015. REUTERS/Suzanne Plunkett

Spectator stands on a mobility scooter to watch Court 16 at the Wimbledon Tennis Championships in London, July 2, 2015. REUTERS/Suzanne Plunkett

Andy Murray of Britain reacts during his match against Robin Haase of the Netherlands at the Wimbledon Tennis Championships in London, July 2, 2015. REUTERS/Henry Browne

Lleyton Hewitt of Australia dives for the ball during his match against Jarkko Nieminen of Finland at the Wimbledon Tennis Championships in London, June 29, 2015. REUTERS/Stefan Wermuth

Yulia Putintseva of Kazakhstan gestures during her match against Venus Williams of the U.S. at the Wimbledon Tennis Championships in London, July 1, 2015. REUTERS/Henry Browne