Tony Mundine has quit as Sonny Bill Williams' trainer for the footy superstar's fight in Brisbane next month, according to a Sydney newspaper.

The Daily Telegraph reported that Mundine would not be in Sonny Bill's corner because of his son Anthony's falling out with the promoter and his former agent Khoder Nasser.

"No I'm not training Sonny Bill," Mundine said, "My son had a blue with Khoder Nasser so that's the end to it.

"I haven't told Sonny Bill yet. I love the boy and I love his brothers. They're good people.

"He's got plenty of ability I wish him well. I just can't be involved while Khoder is involved in the fight.

"Anthony is my son and my only son. Of course I stick by him."

Sonny Bill will fight 44-year-old South African veteran Francois Botha, dubbed the "White Buffalo", on November 24 before joining the Sydney Roosters for his NRL comeback.

Botha is considered way past his best and has lost his past three fights, however Williams believes it will be a step up from his previous fights.

"He's been in there with all the greats. For me, it's a privilege to be able to step in the ring with him," Williams said.

"The thing that adds a bit of spice to it is because of the whole All Black/South Africa factor involve."

Botha has 48 wins and eight losses - two of those defeats coming in world title fights against Lennox Lewis and Wladimir Klitschko.

Botha has also had losses against boxing greats Mike Tyson and Evander Holyfield.