Unranked former South African heavyweight boxing champion Osborne "Big Daddy" Machimana says defeat is not an option in his comeback fight tomorrow night.

A positive result will see his name back in Boxing SA's ratings, and that will enhance his chances of reclaiming the title from Anton Nel. Machimana, who became SA's first black heavyweight champion, forfeited his rating because he has not fought for two years.

The 36-year-old last fought in November 2013 when he was outpointed over 10 rounds by South Africa-based Zimbabwean Elvis Moyo for the WBF Africa title in Cape Town.

Tomorrow he welcomes Cape Town-based Congolese Mugabon Mudimba at Hellenic Hall in Germiston. Their international non-title eight-rounder will headline a development tournament that will be staged by Gilmey Masters with the sole intention of raising funds for two charities.

The tournament is aptly dubbed "Fighting for the Angels".

"This is a must-win fight for me," Machimana said. "Mudimba is a closed book and that is a bit of a worry. But it is not a cause for concern because the team that I have behind me is so good that I am in an amazing mental and physical condition.

"Defeat is out of the question."

At 125kg for his fight against Moyo, Machimana looked more like a sumo wrestler than a boxer. But he now looks fitter and mean - thanks to manager Kathy Deftereos, personal trainer Fabrizio Clarizio and boxing trainer Michele Castellan.