Kei Nishikori beat Novak Djokovic in the 2014 US Open semi-finals
Japan's Kei Nishikori says he "gave it his all" after announcing he will retire from tennis at the end of the 2026 season.
The 36-year-old became the first Japanese player to break into the top 10 and achieved a career-high ranking of number four in the men's standings.
Nishikori, who won bronze at the 2016 Olympics in Rio, became the first player from his country to reach a Grand Slam singles final when he played Marin Cilic for the US Open title in 2014 - a match he lost in straight sets.
He has now dropped to 464 in the men's rankings having been hampered by injuries.
