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MELBOURNE, AUSTRALIA - JANUARY 18: Kei Nishikori of Japan serves in his first round match against Phillip Kohlschreiber of Gemany during day one of the 2016 Australian Open at Melbourne Park on January 18, 2016 in Melbourne, Australia. (Photo by Michael Dodge/Getty Images)

MELBOURNE, AUSTRALIA - JANUARY 18:  Kei Nishikori of Japan serves in his first round match against Phillip Kohlschreiber of Gemany during day one of the 2016 Australian Open at Melbourne Park on January 18, 2016 in Melbourne, Australia.  (Photo by Michael Dodge/Getty Images)