MELBOURNE, AUSTRALIA - JANUARY 12: Kei Nishikori of Japan plays a backhand during a practice session ahead of the 2019 Australian Open at Melbourne Park on January 12, 2019 in Melbourne, Australia. (Photo by Darrian Traynor/Getty Images)
MELBOURNE, AUSTRALIA - JANUARY 12: Kei Nishikori of Japan plays a backhand during a practice session ahead of the 2019 Australian Open at Melbourne Park on January 12, 2019 in Melbourne, Australia. (Photo by Darrian Traynor/Getty Images)