Williams takes a perfect 5-0 record into the fight but the South African is a clear step up from the Roosters recruit's previous bouts, three of which resulted in knock-out wins.
Botha has won 44 of his 60 career fights, 29 by knock-out, over a 23-year career which includes defeats to boxing greats Mike Tyson, Lennox Lewis, Wladimir Klitschko and Evander Holyfield.
He is in the twilight years of his career and goes into Friday's bout having lost his last three fights. But he proved in those bouts that he can still go the distance lasting up to the 10th round in each - a distance Williams has yet to reach during his five fights.
"In real life, he should never have an opportunity to fight a guy like me with just five fights to his name," he said.
"I'm only taking this fight because of his notoriety in rugby."
Last week Williams had praise for his opponent as he eyes an opportunity to defeat a recognised name in the sport.
"His experience speaks for itself," he said.
"For me in a boxing sense I need to take fights like this to move up.
"It's definitely going to put my name out there internationally if I win because it's for a WBA international belt."
- nzherald.co.nz
