Kei Nishikori (born December 29, 1989) is a Japanese professional tennis player who reached a career-high singles ranking of world No. 4, making him the highest-ranked Japanese man in the Open Era. He is best known for his runner-up finish at the 2014 US Open, where he upset world No. 1 Novak Djokovic en route to the final—becoming the only man from an Asian country to contest a major singles final—and for winning a historic bronze medal at the 2016 Rio Olympics by defeating Rafael Nadal, Japan's first Olympic tennis medal in 96 years. Over his career, he has won 12 ATP singles titles and boasts remarkable consistency in extended matches, holding a 78.4% win rate in five-set encounters and a 72.4% win rate in deciding sets. Beginning tennis at age five, Nishikori moved to Florida's IMG Academy at 14 and turned professional in 2007, earning his first ATP quarterfinal appearance at Indianapolis that year. In his personal life, he married in 2020, but in 2025 he faced a public apology after allegations of an affair with a Japanese model emerged.