Australian Open 2018

Tennis - Australian Open - Marin Cilic of Croatia v Vasek Pospisil of Canada - Hisense Arena, Melbourne, Australia, January 15, 2018. Cilic hits a shot. / REUTERS

Australian Open - Rod Laver Arena, Melbourne, Australia, January 22, 2018. The Melbourne skyline is seen in the background during the match between Chung Hyeon of South Korea and Novak Djokovic of Serbia. / REUTERS

Tennis - Australian Open - Rod Laver Arena, Melbourne, Australia, January 16, 2018. Alexander Zverev of Germany stretches for a shot to Thomas Fabbiano of Italy. / REUTERS

Tennis - Australian Open - Rod Laver Arena, Melbourne, Australia, January 22, 2018. Chung Hyeon of South Korea serves against Novak Djokovic of Serbia. / REUTERS

Tennis - Australian Open - Rod Laver Arena, Melbourne, Australia, January 22, 2018. Chung Hyeon of South Korea hits a shot against Novak Djokovic of Serbia. / REUTERS

Tennis - Australian Open - Rod Laver Arena, Melbourne, Australia, January 22, 2018. Novak Djokovic of Serbia hits a shot against Chung Hyeon of South Korea. / REUTERS

Tennis - Australian Open - Rod Laver Arena, Melbourne, Australia, January 20, 2018. Chung Hyeon of South Korea reacts during his match against Alexander Zverev of Germany. / REUTERS

Tennis - Australian Open - Rod Laver Arena, Melbourne, Australia, January 22, 2018. Chung Hyeon of South Korea chats Novak Djokovic of Serbia after Chung won their match. / REUTERS

Tennis - Australian Open - Margaret Court Arena, Melbourne, Australia, January 16, 2018. A fan of Novak Djokovic of Serbia is pictured. / REUTERS

Tennis - Australian Open - Dustin Brown of Germany v Pedro Sousa of Portugal - Melbourne, Australia, January 15, 2018. Brown in action. / REUTERS

Tennis - Australian Open - Rafael Nadal of Spain v Victor Estrella Burgos of Dominican Republic - Rod Laver Arena, Melbourne, Australia, January 15, 2018. Nadal hits a shot. / REUTERS

Tennis - Australian Open - Venus Williams of the U.S. v Belinda Bencic of Switzerland - Rod Laver Arena, Melbourne, Australia, January 15, 2018. Williams hits a shot. / REUTERS

Tennis - Australian Open - Francesca Schiavone of Italy v Jelena Ostapenko of Latvia - Rod Laver Arena, Melbourne, Australia, January 15, 2018. Ostapenko gets up after stretching for a shot. / REUTERS

Tennis - Australian Open - CoCo Vandeweghe of the U.S. v Timea Babos of Hungary - Hisense Arena, Melbourne, Australia, January 15, 2018. The court is wiped during a rain delay. / REUTERS

Tennis - Australian Open - Marin Cilic of Croatia v Vasek Pospisil of Canada - Hisense Arena, Melbourne, Australia, January 15, 2018. Cilic serves. / REUTERS

Tennis - Australian Open - Margaret Court Arena, Melbourne, Australia, January 16, 2018. Caroline Garcia of France signs autographs after winning against Carina Witthoeft of Germany. / REUTERS

Tennis - Australian Open - Rod Laver Arena, Melbourne, Australia, January 20, 2018. Chung Hyeon of South Korea hits a shot against Alexander Zverev of Germany. / REUTERS

Tennis - Australian Open - Sloane Stephens of the U.S. v Zhang Shuai of China - Margaret Court Arena, Melbourne, Australia, January 15, 2018. Zhang hits a shot. / REUTERS

Tennis - Australian Open - Venus Williams of the U.S. v Belinda Bencic of Switzerland - Rod Laver Arena, Melbourne, Australia, January 15, 2018. Williams serves. / REUTERS

ennis - Australian Open - John Isner of the U.S. v Matthew Ebden of Australia - Margaret Court Arena, Melbourne, Australia, January 15, 2018. Ebden celebrates winning the match. / REUTERS

Tennis - Australian Open - Samantha Stosur of Australia v Monica Puig of Puerto Rico - Margaret Court Arena, Melbourne, Australia, January 15, 2018. Puig hits a shot. / REUTERS

Tennis - Australian Open - Jack Sock of the U.S. v Yuichi Sugita of Japan - Melbourne, Australia, January 15, 2018. Sugita celebrates after winning the match. / REUTERS

Tennis - Australian Open - Hisense Arena, Melbourne, Australia, January 16, 2018. Angelique Kerber of Germany signs autographs after winning against Anna-Lena Friedsam of Germany. / REUTERS

Tennis - Australian Open - Quarterfinals - Rod Laver Arena, Melbourne, Australia, January 23, 2018. Spain's Rafael Nadal in action during his match against Croatia's Marin Cilic. / REUTERS

Tennis - Australian Open - Quarterfinals - Rod Laver Arena, Melbourne, Australia, January 23, 2018. Rafael Nadal of Spain leaves after retiring injured in his match against Marin Cilic of Croatia. / REUTERS

Tennis - Australian Open - Quarterfinals - Rod Laver Arena, Melbourne, Australia, January 24, 2018. Chung Hyeon of South Korea stretches for a shot against Tennys Sandgren of the U.S. / REUTERS

Tennis - Australian Open - Quarterfinals - Rod Laver Arena, Melbourne, Australia, January 24, 2018. Chung Hyeon of South Korea celebrates winning against Tennys Sandgren of the U.S. / REUTERS