Last updated on .From the section Boxing

Sonny Bill Williams has been capped for New Zealand in rugby league and rugby union

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 2002: Signs for rugby league team Sydney Bulldogs

2004: Makes Bulldogs debut aged 18, and New Zealand Test debut months later

2008: Leaves the Bulldogs to sign for French rugby union club Toulon, again debuting for the national side within months

2009: Makes professional boxing debut

2011: Signs for New Zealand Super Rugby team Crusaders and is part of the All Blacks side that wins the Rugby World Cup in October

2012: 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.