
Kostya Tszyu (born 1969) is considered one of the greatest junior welterweights of all time, a unified world champion born in Russia who built his legacy fighting out of Australia.
Tszyu combined elite amateur technique with professional-level power — a rare combination. His 2001 KO of Zab Judah to unify the junior welterweight division is one of the great performances in the weight class's history.
Reference:
TaskLoco™ — The Sticky Note GOAT