Williams sparred with Knights second-rower Cory Paterson and former Australian heavyweight Bob Mirovic at the Tuff'n Up boxing gym, in Newcastle West, last night while good friend Mundine looked on.

Williams was scheduled to fight 36-year-old Campbelltown brawler Scott Lewis on January 29 at Newcastle Entertainment Centre in his third boxing bout.

The bout was moved to the Gold Coast last month to cross-promote Williams's Super rugby team, the Crusaders, and their pre-season trial against Queensland.

Khoder Nasser, who manages Williams and Mundine, said they chose to base themselves in Newcastle for three days due to their close affiliation with the city.

"We organised to train here because Newcastle is a boxing town," Nasser said.

"The boys have enjoyed coming here in the past.

"Sonny has got friendships with several of the boys up here."

Nasser said there were no plans to bring a bout to Newcastle any time soon.

Williams, a former Canterbury Bulldogs second-rower, has won his two boxing bouts via knockout, against rookies Ryan Hogan and Gary Gurr.

Mundine is no stranger to Newcastle.

The two-time World Boxing Association super-middleweight and current International Boxing Organisation middleweight champion has fought in Newcastle twice during his 44-bout professional career, against Ruben Eduardo Acosta in November 2006 and Japan's Crazy Kim in July 2008.

During his preparations for his technical knockout victory over Acosta, Mundine based himself at Tuff'n Up.