He won a silver medal at the 2003 World Amateur Boxing Championships at 201 lbs losing to his nemesis Odlanier Solís.

There he was narrowly defeated in the first round of the heavyweight (91 kg) division by Cuba's eventual winner Odlanier Solís.

He turned pro in Germany as a cruiserweight in January 2006 and he defeated Tomáš Mrázek with a first-round knockout in his first fight.

[1] He was slated to fight Garrett Wilson on 22 February 2013 in Galaţi, Romania, for the IBF cruiserweight title eliminator.

Alekseyev won via unanimous decision becoming the mandatory for the IBF world title (currently held by Yoan Pablo Hernández).