Novak Djokovic of Serbia celebrates after match point in his straight sets victory over Kei Nishikori of Japan in their semifinal match in Arthur Ashe Stadium at the 2018 US Open Tennis Championships at the USTA Billie Jean King National Tennis Center in New York City on September 7, 2018. Photo by /UPI, Image: 385796591, License: Rights-managed, Restrictions: , Model Release: no, Credit line: Profimedia, UPI