(1), 6–3, becoming the first Japanese man to win an Olympic tennis medal since Ichiya Kumagae in the 1920 Summer Olympics. Nishikori nearly replicated his 2014 US Open run by reaching the semifinals of the US Open, defeating Benjamin Becker, Karen Khachanov and Nicolas Mahut respectively in four sets, followed by a straight sets fourth-round win against Ivo Karlović, and a 5-set victory over world No. 2 Andy Murray in the quarterfinals that lasted nearly 4 hours; this was arguably his biggest victory since the 2014 US Open. After leading by a set and a break against eventual champion Stan Wawrinka in the semifinals, a clearly fatigued Nishikori lost in 4 sets, hence ending his U.S hardcourt season with a finals and semifinals run in the Canadian Open and the US Open respectively. After an indifferent Asian swing season where he retired in his home tournament, the Rakuten Japan Open, Nishikori returned to action again in Basel, where he was the No. 3 seed. He enjoyed a successful tournament there, but lost to Marin Čilić in the finals. Nishikori next represented Japan in the Davis Cup Play-Off against Ukraine and played in the doubles rubber alongside Yūichi Sugita, winning the match in straight sets, giving Japan an unassailable 3–0 lead to promote his country back into the 2017 Davis Cup World Group. Nishikori made his third successive appearance at the year-end championships after becoming the fifth player to qualify for the 2016 ATP World Tour Finals. He won his first match, upsetting third seed, Stan Wawrinka in straight sets 6–2, 6–3 before losing his other two round-robin matches to Andy Murray and Marin Čilić respectively, both in three sets. Having done enough to nevertheless make the semifinals however, he was then defeated by a resurgent Novak Djokovic in straight sets, ending his season with a singles ranking of world No. 5 for both the second time in his career and in the past three years as well. 2017: Wrist injury and out of the top 20 Nishikori began the year by reaching the finals of Brisbane, beating Wawrinka along the way, before falling to champion Grigor Dimitrov. In the Australian Open, after defeating Andrey Kuznetsov in five sets in the first round, Kei beat his next two opponents in straight sets. His run ended in another five-set match to eventual champion Roger Federer. Nishikori withdrew from the US Open in