Novak Djokovic

Serbia's Novak Djokovic falls as he defeats Britain's Andy Murray during their final match of the French Open tennis tournament at the Roland Garros stadium.

Alastair Grant/AP

Serbia’s Novak Djokovic falls as he defeats Britain’s Andy Murray during their final match of the French Open tennis tournament at the Roland Garros stadium

Serbia's Novak Djokovic returns in his first round match of the French Open tennis tournament against Yen-Hsun Lu of Taiwan at the Roland Garros stadium in Paris, France, Tuesday, May 24, 2016.

Michel Euler/ AP Photo

Serbia’s Novak Djokovic returns in his first round match of the French Open tennis tournament against Yen-Hsun Lu of Taiwan at the Roland Garros stadium in Paris, France.

Novak Djokovic of Serbia prepares to serve to  Andreas Seppi of Italy during their third round match at the Australian Open tennis championships in Melbourne, Australia, Friday, Jan. 22, 2016.(AP Photo/Andrew Brownbill)

Andrew Brownbill/AP

Novak Djokovic of Serbia prepares to serve to Andreas Seppi of Italy during their third round match at the Australian Open tennis championships in Melbourne, Australia

Jason Reed/Reuters

Serbia’s Novak Djokovic serves during his first round match against South Korea’s Hyeon Chung at the Australian Open tennis tournament at Melbourne Park, Australia 

Novak Djokovic of Serbia hits a return against John Isner of U.S. during their men's singles match at the China Open tennis tournament in Beijing, China, October 9, 2015.

Kim Kyung-Hoon/Reuters

Novak Djokovic of Serbia hits a return against John Isner of U.S. during their men’s singles match at the China Open tennis tournament in Beijing, China

Novak Djokovic celebrates a break of serve against Kevin Anderson during day Seven of the Wimbledon Championships at the All England Lawn Tennis and Croquet Club, Wimbledon. PRESS ASSOCIATION Photo. Picture date: Tuesday July 7, 2015

Dominic Lipinski/PA

Novak Djokovic celebrates a break of serve against Kevin Anderson during day Seven of the Wimbledon Championships at the All England Lawn Tennis and Croquet Club, Wimbledon

Workers sweep water off a tarp as rain interrupts a men's singles match between Djokovic of Serbia and Sousa of Portugal at the French Open tennis tournament at the Roland Garros stadium in Paris...Workers sweep water off a tarp as rain interrupts a men's singles match between Novak Djokovic of Serbia and Joao Sousa of Portugal at the French Open tennis tournament at the Roland Garros stadium in Paris May 26, 2014.     REUTERS/Gonzalo Fuentes

Gonzalo Fuentes/Reuters

Workers sweep water off tarpaulin as rain interrupts the men’s singles match between Novak Djokovic of Serbia and Joao Sousa of Portugal at the French Open tennis tournament, Roland Garros stadium, Paris

Novak Djokovic of Serbia signs autographs after his men's singles match against Lukas Lacko of Slovakia at the Australian Open 2014 tennis tournament in Melbourne

David Gray/Reuters

Novak Djokovic of Serbia signs autographs after his men’s singles match against Lukas Lacko of Slovakia at the Australian Open 2014 tennis tournament in Melbourne. Djokovic won 6-3 7-6 (7-2) 6-1.

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Anja Niedringhaus/AP

Andy Murray of Britain reacts on defeating Novak Djokovic of Serbia during the men’s singles final match at the All England Lawn Tennis Championships in Wimbledon, London, Sunday

Tennis - 2013 Wimbledon Championships - Day Thirteen - The All England Lawn Tennis and Croquet Club...Fans react on Murray Mount as they watch Great Britain's Andy Murray play Serbia's Novak Djokovic in their Men's Final, on the big screen during day thirteen of the Wimbledon Championships at The All England Lawn Tennis and Croquet Club, Wimbledon. PRESS ASSOCIATION Photo. Picture date: Sunday July 7, 2013. See PA story TENNIS Wimbledon. Photo credit should read: Dominic Lipinski/PA Wire.  RESTRICTIONS: Editorial use only. No commercial use. No video emulation. No use with any unofficial third party logos.

Dominic Lipinski/PA

Fans react on Murray Mount as they watch on the big screen Great Britain’s Andy Murray play Serbia’s Novak Djokovic in the men’s grand slam final of the Wimbledon tennis Championships at The All England Lawn Tennis and Croquet Club, Wimbledon, UK. Murray won in three sets, 6-4 7-5 6-4, and became the first British men’s player to take the trophy for 77 years