Elena Vyacheslavovna Dementieva (pronounced: Russian pronunciation: [dʲɪˈmʲentjɪvə] Russian: Елена Вячеславовна Дементьева (help·info)); born October 15, 1981, Moscow), is a professional tennis player from Russia.
Dementieva played and won her first international tournament, Les Petit As, in France at the age of 13. In 1997, she entered the WTA top 500. She turned professional in 1998 and entered the top 100 in 1999.
In 1999, Dementieva represented Russia in the Fed Cup final against the United States, scoring Russia's only point when she upset Venus Williams 1–6, 6–3, 7–6(5), recovering from a 4–1 third set deficit. She played her first Grand Slam main draws, qualifying for the Australian Open, French Open, and Wimbledon and receiving a direct entry into the US Open. She reached the second round at the Australian Open and French Open, made a first round exit at Wimbledon, and reached the third round of the US Open.