Efforts to get Sonny Bill Williams to renew his New Zealand Rugby Union contract have taken a new twist with Williams' ally, boxer Anthony Mundine, taking a swipe at the All Black coaches.

Williams could not even make the bench for Saturday's Tri-Nations decider between the All Blacks and the Wallabies in Brisbane and head coach Graham Henry said he rated incumbent Ma'a Nonu as the best No.12 in the world.

Unlike most of the other All Blacks, Williams has yet to re-sign with the NZRU beyond the looming World Cup with the protracted negotiations stumbling over a sponsorship clash.

Williams' manager Khoder Nasser wants compensation for his star player after the NZRU vetoed a sponsorship deal for Williams to endorse a product that is a rival to an All Blacks sponsor.

Williams management also knows a high profile World Cup would add enormously to the player's value but that appeared to be a fading hope after Henry was unable to even find a place for Williams on the bench against Australia.

"He'll get his opportunity, [but] can he be better than the best No.12 in the world?" Henry said, comparing Williams with Nonu.

He said Williams may have been a first-choice selection in other teams he's played for in a high-profile Rugby League and Rugby Union career, but with strong competition in the All Blacks camp "he's not guaranteed a run-on spot".

Mundine, a former World boxing champion and another member of the Nasser stable, joined the debate about Williams with a series of tweets Saturday questioning whether it was more than just form that lead to Williams' omission from the Wallabies Test.

"Why the hell ain't the all blacks playing SBW ... I think it's crazy??? he one of best if not the best backs in game!!! is there an agenda???" he tweeted, adding that Nonu "was not on the same level" as Williams.

"There gotta questions ask if he don't Start the world cup."

AFP