Daniel Mark Nestor ( NES-tər; Serbian: Данијел Нестор, romanized: Danijel Nestor; born Danijel Nestorović, September 4, 1972) is a Canadian former professional tennis player. He was ranked as the world No. 1 in men's doubles by the Association of Tennis Professionals (ATP) for 108 weeks (fifth-most of all time). Nestor won 95 ATP Tour-level doubles titles, including twelve majors (eight in men's doubles and four in mixed doubles), an Olympic gold medal at the 2000 Sydney Olympics, and four Tour Finals. Nestor was the first man to complete the Big Titles sweep in doubles (winning every major and Masters event, the Tour Finals, and an Olympic gold medal over the course of a career), an achievement only matched by the Bryan brothers. He was part of the ATP Doubles Team of the Year in 2002 and 2004 (with Mark Knowles), and 2008 (with Nenad Zimonjić).
Nestor is widely considered one of the foremost doubles players in history, due to his longevity and continued success at the top of the game. As of March 2018, he is 10th for the most ATP Tour titles in Open Era history, and has the third-highest tally for doubles titles. In January 2016, Nestor became the first doubles player in ATP history to win 1000 matches. He was continuously ranked in the top 100 in doubles from April 1994 to April 2018, a total of 1134 consecutive weeks. Nestor retired at the end of the 2018 season, ending a 27-year career.
