Nikolay Vladimirovich Davydenko (Russian: Никола́й Влади́мирович Давыде́нко, tr. Nikolaj Vladimirovič Davydenko; IPA: ) is a Russian former professional tennis player. He achieved a career-high singles ranking of World No. 3 in November 2006. Davydenko's best result in a Grand Slam tournament was reaching the semi-finals, which he accomplished on four occasions: twice each at the French Open and the U.S. Open, losing to Roger Federer in all but one of them. His biggest achievement was winning the 2009 ATP World Tour Finals, and he also won three ATP Masters Series. In mid-October 2014 Davydenko retired from competitions.