World Cup-winning rugby star Sonny Bill Williams won the New Zealand heavyweight title with a first-round knockout of Clarence Tillman.
Williams, who played the final four minutes of
the All Blacks' victory over France
in October, beat veteran Tillman with a second of round one remaining.
The win means Williams has won all five of his professional bouts, three of them by way of knockout.
The 26-year-old gave away 44lb in weight to his American opponent.
Sonny Bill Williams
Signs for rugby league team Sydney Bulldogs
Makes Bulldogs debut aged 18, and New Zealand Test debut months later
Leaves the Bulldogs to sign for French rugby union club Toulon, again debuting for the national side within months
Makes professional boxing debut
Signs for New Zealand Super Rugby team Crusaders and is part of the All Blacks side that wins the Rugby World Cup in October
Wins vacant New Zealand heavyweight title in Hamilton
Williams is competing as a boxer on a part-time basis before he starts the 2012 Super Rugby campaign with the Waikato Chiefs, for whom he signed after last year's Rugby World Cup.
Williams was originally scheduled to take on Richard Tutaki for the crown vacated by Shane Cameron but Tutaki's arrest on drug charges saw 34-year-old Tillman drafted in as a late replacement.
After the two boxers sounded each other out early in the clash in Hamilton, New Zealand, Williams connected with a good left hook and finished Tillman off with a flurry of blows that left his opponent with his head hanging out of the ring.
There was plenty of ill feeling going into the clash after the fighters' altercation at Tuesday's weigh-in and that continued during the fight, with the duo having to be separated as they banged shoulders and exchanged words.