Francois Botha says Sonny Bill Williams will be "known as garbage" in boxing circles if he doesn't take a rematch though the South African heavyweight has doubts the multi-talented Kiwi sportsman will get back in the ring with him.
Williams beat Botha on points in Brisbane earlier this month, in a bout full of controversy that included allegations of match-fixing, bribery and doping.
The managers of the two boxers have spoken of a rematch in South Africa in December - once Williams is free of his NRL commitments. Botha believes that is the only way for Williams, a boxing novice, to gain respect.
Williams won the WBA International belt in Brisbane but Botha says he wouldn't be surprised if Williams gave that up, rather than fight him again.
"I think he is going to give it up (the WBA International title). He had a little taste of deep water and he didn't like it. He almost drowned," Botha told specialist boxing radio station ATG.
"Hopefully he will do it. If not his profession (sic) will be diminished. He will never be respected. I hope for his sake he will take it and come fight the Buffalo. Otherwise Sonny Bill Williams will never be the same. He will never be a high level athlete and will be known as garbage!"
The 44-year-old Botha was at his trash-talking best as he spoke to respected radio host Tim Kudgis about the Brisbane shambles.
"This boy Sonny Bill Williams has no option but to fight the White Buffalo again," he said.
"There was a contract that was signed when Sonny Bill Williams came to South Africa about a year and a half ago. That was a 10 round bout here in South Africa. That fight never took place."
He claimed in his recent discussions with the WBA, measures would be taken to ensure a rematch would be free of the controversies of the first fight that included it mysteriously being cut from 12 to 10 rounds.
"There is going to be no match-fixing or doping. It is going to be for the WBA International Championship in South Africa - where the real men are going to come out. He has no choice but to fight the Buffalo."
Botha could be in action in New Zealand in May if plans to have him fight rising New Zealand heavyweight Joseph Parker materialise.
Parker's promoters Duco Events say they have "agreed to terms" with Botha's management but a contract is yet to be signed.