But that hasn't stopped former IBF champion, hardened South African veteran Francois Botha, wanting to dish out another lesson to the ex-All Black in their WBA international heavyweight title bout in Brisbane on Friday night.
Mundine's arrival in the Williams camp on Wednesday should ensure plenty of colour ahead of the Sydney Roosters recruit's biggest fight to date.
However, Williams, 27, vowed to do all his talking in the ring after the fallout over his support of Mundine on Twitter following the IBF middleweight title loss to compatriot Daniel Geale in Sydney last week.
Williams contemplated being hit with legal action before apologising for his tweet of a photo of himself, Wallabies five-eighth Quade Cooper and Mundine after the Geale fight, with the caption: "Hanging out with @Anthony-Mundine celebrating a victory. We don't pay attention to corrupt judges!"
Unlike Mundine who insisted he was "robbed" after the Geale fight, Williams (5-0 boxing record) was sheepish when reminded of his chip ahead of his daunting clash with 44-year-old Botha (48-8-3).
"At the time we were full of emotion. Sometimes you do silly things like that," he said.
"I meant no disrespect to the Geale camp. He is a great fighter and champion.
"The next morning I apologised. When you have nothing nice to say you should keep it to yourself."
Cooper - who makes his professional boxing debut against former Muay Thai title contender Barry Dunnett on the Williams undercard - was not so apologetic.
"I have no more comment to make on that. It is done and dusted. I am going to support him (Mundine) 100 per cent no matter what," he said as he trained on Tuesday.
"He has always been a great friend of mine. I will be there for him as well."
But Botha - dubbed "The White Buffalo" - was keen to ruffle feathers, claiming the "green" Williams had no right to be in the same ring with him.
"He's got some balls to pick this fight, and I am not talking rugby balls," Botha said.
"No one else at his stage of his career would pick a fight like that."
Williams curiously revealed that the extent of his boxing training was once watching fights on YouTube but felt he was ready to down Botha under the expert tutelage of renowned task master Mick Akkaway.
But it seems Williams has to work on his own YouTube highlights judging by Botha's assessment.
"You really want to know? Um, he's very green," Botha said of Williams.
"On stats alone he shouldn't be in the ring with me. But I won't underestimate him."
Williams reiterated that he would hang up the gloves if knocked out on Friday night.
"If I can't beat guys like this then there is no future for me in the sport," he said.