Chagaev won the WBA title in 2007 with a majority decision victory over Nikolai Valuev, but was made "champion in recess" after he sustained an injury. He relinquished the title after failing to have a rematch with Valuev. In his next fight, Chagaev lost by stoppage to IBF, WBO and IBO Champion Wladimir Klitschko.
Chagaev, a two-time world amateur champion, defeated legendary Cuban boxer Félix Savón to capture the gold medal at the 1997 World Championships but was then stripped of his crown for having two professional fights prior to the championships. Chagaev was reinstated as an amateur the following year when the fights were declared exhibitions.
1995 Won the gold medal at the Asian Championships in Tashkent, Uzbekistan at Heavyweight.