Rugby: Question of when, not if, Roger Tuivasa-Sheck becomes an All Black, says Sonny Bill Williams

It's a question of when, and not if, Roger Tuivasa-Sheck makes it into the All Blacks after his switch from NZ Warriors, says fellow cross-code star Sonny Bill Williams.

On Thursday, 28-year-old Tuivasa-Sheck said farewell to his Warriors teammates, as he returns to New Zealand to reignite his rugby union ambitions.

Tuivasa-Sheck will turn out for Auckland in the upcoming NPC, and will have his eyes on selection for the All Blacks' end of year tour squad.

The now former Warriors captain won't have to look too far for inspiration in his quest to become an All Black, with former teammate Williams having done the same, leaving the Bulldogs to make the 2011 Rugby World Cup squad.

Tuivasa-Sheck and Williams were both stars of Auckland schoolboy rugby, for Otahuhu College and Mount Albert Grammar respectively, before being lured across the Tasman to the NRL.

And having made the code switch himself, Williams backs his former Sydney Roosters teammate to succeed in the 15-man code.

"For me, it's not a case of will he make it to the All Blacks or will he thrive in the game of 15, it's a question of how long it'll take," Williams told Channel Nine.

"We've got to remember that he grew up as a rugby player and league boys poached him from the game of rugby and brought him across, so he shouldn't have too much [sic] problems transitioning back.

"He is humble and he's kept that hard-working approach all throughout his career. When you add that quality to the freakish God-given talent that he has, you get what you get.

"What Roger also represents is he is a boy from South Auckland, a predominantly low-income area, and he's made it. 

"He's thrived on the biggest stage so a lot of young guys who come from that similar background see him as an inspiration."

Williams also added his weight into what position Tuivasa-Sheck will initially play, having been speculated for a berth in either midfield, or the outside backs.

"I think he'll play wing in the early stages of his transition," Williams says.