Daniil Ostapenkov (born May 8, 2003) is a Belarusian professional tennis player. He achieved a career-high junior ITF ranking of world No. 48. He has a career high singles ranking of No. 703 achieved on 27 October 2025 and a career high doubles ranking of No. 261 achieved on 24 November 2025.
Ostapenkov is best known for his shocking upset win, in straight sets, over world No. 15 and former world No. 8 Diego Schwartzman during a Davis Cup match against Argentina.[1] At the time, Ostapenkov did not have an ATP ranking.