But his trainer Harold Volbrecht is confident that the errant boxer will prove to detractors that he has mended his ways.
“Tommy has been impressive in the gym and those who are counting him out will get the surprise of their lives,” Volbrecht says.
The veteran trainer knows better as he was with the left hander during his rise to fame.
This when Oosthuizen was considered the best boxer in the land having won several regional titles before adding the IBO super middleweight title to his collection.
He took his talent abroad where he quickly won over the hearts of partisan American fans and shot up the lofty rankings of several major world bodies including the respected Ring Magazine list.
With Rodney Berman shrewdly pushing him for a world title shot after several impressive wins over US prospects, Oosthuizen suddenly went off the rails.
Berman stuck with him but the fighter kept disappointing him until he could not take it anymore. But now “Tommy Gun” is back after several brushes with the law and seems to have rehabilitated.
Berman says he has also been impressed by Oosthuizen's desire to recapture his form.
“Obviously I would not have given him this opportunity unless I was convinced that he had mended his ways,” he said.
For all his wayward ways, Oosthuizen still boasts an impressive fight record of a single loss in 30 bouts.
A fit and motivated Oosthuizen is a handful to any opponent including Mchunu who is also using the fight to get back to the summit of the division.
Mchunu, also a left hander, is at the twilight of his career with every fight he engages in being crucial to determine his ascent or demise.
He is still blessed with an abundance of skills which should have taken him far but somehow he fell short.
However, he may argue against all four of his losses in 23 bouts including the nine-round stoppage defeat by universally recognised undisputed king of the division Oleksandr Usyk when he challenged for his WBO crown.
“This is one of the most eagerly anticipated fights in South Africa for many yeas,” Berman said. “The tickets were sold out several weeks ago.”
The fight will be shown live on SuperSport from 7pm.