Denis Istomin (born September 7, 1986 in Orenburg, Russian SFSR, Soviet Union) is a professional Uzbek tennis player. His career high rank is #39, achieved on August 30, 2010. He is coached by his mother.
Istomin broke into the top–200 late in 2005 and finished the year at #196.
Istomin received the Asian Wildcard into the 2006 Australian Open where he played world number one Roger Federer. Federer won in three straight sets, 6–2, 6–3, 6–2. He spent much of 2006 in the top–200, reaching a career-high of #186 on May 1, and finished the year at #200 in singles.