Sonny Bill Williams is already contemplating his next bout after claiming the New Zealand Professional Boxing Association heavyweight title with a first-round stoppage of American Clarence Tillman in Hamilton.

Williams, who now turns his immediate attention to the Chiefs’ Super rugby campaign, told the crowd after the fight on Wednesday night that he might get back into the ring during the season.

“In saying that, I just have to see how my boys are going on the footy field,” he said.

“If everything falls into place, we’ll do it, but we’ll cross that bridge when we get there.”

Victory over the Auckland-based Tillman takes the All Black and former Kiwi rugby league Test representative’s boxing record to five wins from five bouts.

After a cagey start by both men, Williams produced a left hook late in the opening round that had Tillman wobbling.

He landed a series of further blows before the referee stopped the scheduled 10-round contest.

The loss was the 34-year-old Tillman’s ninth of a career that has included 11 wins and two draws.

Tillman was a late replacement after the original opponent, Richard Tutaki, was dropped when he was found to be facing criminal charges.

The fight was preceded by a melee at the weigh-in on Tuesday when, after some pushing during the traditional face-off, Tillman threw a glancing right at Williams’ chin before being tackled to the ground.

Williams said the incident served to stiffen his resolve.

“He caught me by surprise,” he said.

“I thought it was just push and shove and he tagged me. That gave me extra motivation to come and try to tag him. God willing, it all worked out.”

He admitted he had been nervous before the bout and he was pleased it was out of the way.

“Probably, on the world stage, it’s just a blip,” he said of the belt he has won.

“But for me … this was my world title.”

Williams has had his doubters ever since he first stepped into the ring in 2009 and he thanked Australian boxing legend Tony Mundine, who prepared him for the Tillman fight, for helping him with the basics of the sport.

“He took me back to the old school,” Williams said.

Mundine, whose son Anthony Mundine was also in Williams’ corner, praised his charge’s performance.

“I thought he fought a great fight,” Mundine said.

“He was a bit nervous, but it’s one of those things that a young guy like him goes through. I think, myself, he can go a long way.”

While he hadn’t expected the bout to last just one round, Mundine had felt that Tillman was “pretty slow and open to be hit”.