Rafael Nadal of Spain struggles to take his shirt off during a break between games of his match against Thomaz Bellucci of Brazil at the Wimbledon Tennis Championships in London, June 30, 2015. REUTERS/Stefan Wermuth 

Dustin Brown of Germany's hair during his match against Yen-Hsun Lu of Taiwan at the Wimbledon Tennis Championships in London, June 30, 2015. REUTERS/Henry Browne 

Jana Cepelova of Slovakia keeps her eye on the ball during her match against Simona Halep of Romania at the Wimbledon Tennis Championships in London, June 30, 2015. REUTERS/Stefan Wermuth 

Nick Kyrgios of Australia hugs a ball boy during his match against Richard Gasquet of France at the Wimbledon Tennis Championships in London, July 6, 2015. REUTERS/Henry Browne 

Belinda Bencic of Switzerland wipes her face during her match against Anna-Lena Friedsam of Germany at the Wimbledon Tennis Championships in London, July 1, 2015. REUTERS/Stefan Wermuth 

Stan Wawrinka of Switzerland prepares to serve during his match against Victor Estrella Burgos of Dominican Republic at the Wimbledon Tennis Championships in London, July 1, 2015. REUTERS/Suzanne Plunkett

Marin Cilic of Croatia reacts reacts to losing the fourth set during his match against John Isner of the U.S.A. at the Wimbledon Tennis Championships in London, July 3, 2015. REUTERS/Toby Melville

Andy Murray of Britain's wedding ring is tied into his shoe laces as he serves during his match against Ivo Karlovic of Croatia at the Wimbledon Tennis Championships in London, July 6, 2015. REUTERS/Toby Melville

Garbine Muguruza of Spain celebrates after winning her match against Timea Bacsinszky of Switzerland at the Wimbledon Tennis Championships in London, July 7, 2015. REUTERS/Suzanne Plunkett 

Novak Djokovic of Serbia wipes his face during his match against Kevin Anderson of South Africa at the Wimbledon Tennis Championships in London, July 7, 2015. REUTERS/Henry Browne

Roger Federer of Switzerland serves during his match against Roberto Bautista Agut of Spain at the Wimbledon Tennis Championships in London, July 6, 2015. REUTERS/Toby Melville

Maria Sharapova of Russia reacts to breaking serve during her match against Coco Vandeweghe of the U.S.A. at the Wimbledon Tennis Championships in London, July 7, 2015. REUTERS/Toby Melville

Novak Djokovic of Serbia pats the ground after winning his match against Kevin Anderson of South Africa at the Wimbledon Tennis Championships in London, July 7, 2015. REUTERS/Henry Browne

Agnieszka Radwanska of Poland gets up after slipping during her match against Jelena Jankovic of Serbia at the Wimbledon Tennis Championships in London, July 6, 2015. REUTERS/Stefan Wermuth 

Kim Murray shares a joke with Great Britain Davis Cup Captain, Leon Smith during the match between Andy Murray of Britain and Ivo Karlovic of Croatia at the Wimbledon Tennis Championships in London, July 6, 2015. REUTERS/Toby Melville

Serena Williams of the U.S.A. serves during her match against Venus Williams of the U.S.A. at the Wimbledon Tennis Championships in London, July 6, 2015. REUTERS/Toby Melville