Auckland - All Blacks star Sonny Bill Williams has given another indication he will return to the NRL by refusing to extend his relationship with New Zealand rugby's biggest sponsor.

VIDEO: Sonny Bill Williams weigh-in brawl

Williams's management has so far rebuffed approaches by adidas to extend his endorsement of its sports clothing.

Adidas signed Williams to be part of its global rugby stable last year, and at the time the deal was hailed an important factor in his decision to commit to New Zealand rugby - the group providing the additional income and profile the Williams camp sought.

But it appears the relationship might have cooled a little, although adidas is known to covet the popularity of the code-hopping Williams, who continues to mix his boxing ambitions with his rugby career.

There is also strong evidence the member of last year's World Cup-winning squad is set to return to the NRL and sign with the Sydney Roosters next year.

It's also believed the 26-year-old Williams is being lined up for a potentially huge deal with Quade Cooper, who is also managed by Khoder Nasser. Cooper's contract with Australian rugby finishes at the end of this year.

Williams's reluctance to cosy up to adidas could lend credibility to the theory he plans to return to the league. It is understood the most recent adidas proposal sought a commitment from Williams that he would stay in the 15-man code beyond this year. This is believed to be the reason for Nasser's opposition to extending the deal.

It has been noticeable that Williams has not worn any adidas regalia in preparation for his bout against American heavyweight Clarence Tillman in Hamilton, New Zealand, on Wednesday night.