He still expects to be a big hit upon his NRL return next year but Sonny Bill Williams concedes he will have to change his tackling approach thanks to the controversial shoulder charge ban.

Williams' main priority is putting his recovering pectoral muscle to the test in a WBA international heavyweight boxing bout with South African veteran Francois Botha in Brisbane on February 8.

But Williams is already sweating on his long awaited rugby league comeback with the Sydney Roosters in their season opener against South Sydney on March 7.

Williams was one of the most spectacular exponents of the charge during his previous NRL stint with the Bulldogs and had looked forward to compiling another highlights package in 2013.


"I don't know if I can tackle now," Williams joked about the ARL Commission's decision to outlaw the act on health recommendations.

However, the ex-All Blacks powerhouse believed the ARLC could have done more to keep the shoulder charge in the game.

"When I was in rugby league nine out of 10 of my tackles were shoulder charges but they never hit the head area," Williams said.

"I would have liked to have seen more bans in place before they cut it off completely then you would have got the players who could do it.

"It's a special thing if you can do it.

"But they are the bosses. I may have to bring my tackle technique over from rugby (where the charge has long been banned)."

However, Williams has more pressing concerns.

The sport-hopping Kiwi admitted he was taking a big risk taking on 44-year-old Botha, a former world champion.

Dubbed the "White Buffalo", Botha has a resume boasting fights against boxing's who's who, including Mike Tyson, Lennox Lewis and Evander Holyfield.

"The only advantage I have is age," said the 27-year-old Williams, the New Zealand heavyweight champion.

"It's a massive step up.

"He's fought some of the best in the business and I only have respect for him.

"I have met him a few times and he is a gentleman but once I get in there he will want to knock my head off.

"It's a big challenge but I feel this is the right direction for me."