World Cup-winning All Black Sonny Bill Williams added another crown to his career on Friday after beating veteran boxer Frans Botha.

Williams, who won the Rugby World Cup with the All Blacks in 2011, survived a whirlwind finish from South African Botha to land the vacant title with a unanimous points decision in Brisbane.

The ringside judges gave him the fight 97-91, 98-94, 97-91 over the 10 rounds.

Williams was holding on in the final round as 44-year-old Botha, dubbed the "White Buffalo", went after him with heavy blows.

Williams, 27, who remains unbeaten in six fights, is due to play in Australia's National Rugby League this year with the Sydney Roosters.

Botha's record now stands at 48-10-3.

Wallabies flyhalf Quade Cooper won his first professional fight on the same fight card in a first-round knockout of fellow Australian Barry Dunnett.

Cooper landed a right hook high on Dunnett's head to send his opponent crashing to the canvas inside the opening round of his scheduled four-round cruiserweight bout.

AFP