At the 2004 Summer Olympics in Athens, Vasiliev qualified as an individual swimmer for the men's 200 m freestyle. He cleared a FINA B-standard entry time of 1:54.94 from the World Championships in Barcelona, Spain. He challenged seven other swimmers in heat two, including dual citizen Mihail Alexandrov of Bulgaria. He rounded out the field to last place by less than 0.18 of a second behind Kazakhstan's Vitaliy Khan, outside his entry time of 1:56.93. Vasiliev failed to advance into the semifinals, as he placed fifty-seventh overall in the preliminaries.