TOKYO, JAPAN - OCTOBER 05: Borna Coric of Croatia competes against Kei Nishikori of Japan during the men's singles match on day one of Rakuten Open 2015 at Ariake Colosseum on October 5, 2015 in Tokyo, Japan. (Photo by Atsushi Tomura/Getty Images)
TOKYO, JAPAN - OCTOBER 05: Borna Coric of Croatia competes against Kei Nishikori of Japan during the men's singles match on day one of Rakuten Open 2015 at Ariake Colosseum on October 5, 2015 in Tokyo, Japan. (Photo by Atsushi Tomura/Getty Images)