SONNY BILL WILLIAMS is looking increasingly likely to quit New Zealand rugby after the World Cup as protracted contract negotiations with the national union continue to sour.

A sponsorship row has erupted between Williams's manager, Khoder Nasser, and the NZRU after it ruled out a personal endorsement deal. Nasser could not be reached for comment, but sources close to Williams said the Crusaders star's continued non-selection in the All Blacks XV was ''agenda-driven''. His close friend, league star turned boxing champion Anthony Mundine, tweeted yesterday to urge the former Canterbury Bulldogs NRL star to quit New Zealand rugby. Williams, who is off contract after the World Cup, signalled to the NZRU this month he would re-sign for another season but might have a change of heart after limited All Blacks game time and the sponsorship disagreement.

Despite a strong Super Rugby season, Williams is behind Ma'a Nonu and Conrad Smith in the World Cup pecking order. In 15 matches for the Crusaders this year, he scored five tries compared to Nonu's three in 12. ''Bra the more I think of this bullshit the more I think I gotta get yu (sic) out of that environment,'' Mundine tweeted to Williams.