Romanchuk participated in the open weight class super heavyweight at the 2005 World Amateur Boxing Championships where he defeated Rustam Saidov and future world champion Roberto Cammarelle 34:27 in the semis but lost the final to Odlanier Solis whom he had beaten on other occasions.

[1] Back at 201 lbs, he was sensationally upset at the 2006 European Amateur Boxing Championships by Ukrainian puncher Denis Poyatsika who managed to stop him in the final.

In 2007, he surprisingly lost to his compatriot and fellow southpaw Rakhim Chakhkeiv and could not go to the World Championships in Chicago.

On 28 July 2008, Romanchuk was arrested by the police in Vladivostok, Russia, for shooting a man in the eye in a drunken fight.

He was convicted of "murder committed with excessive force in self-defense" and sentenced to 1 year 6 months of imprisonment on 27 March 2009.