All Blacks coach Steve Hansen has predicted Sonny Bill Williams will finish as a rugby union great as he sets his sights on a record third consecutive Rugby World Cup triumph with New Zealand.

Dual international Williams, 30, ended speculation about possible moves to European rugby or back to the NRL on Wednesday by recommitting to New Zealand Rugby until the end of the 2019 World Cup year.

He said he actually made the decision to stay – and to change his usual practice of signing one-year deals – soon after playing in New Zealand’s World Cup triumph in Britain last year, when Hansen rang him.

“When you have probably the best coach ever from the 15-man game telling you that you are part of his plans moving forward, that really means a lot,” Williams said.

“Straight after that call, I pretty much got on to my manager and told him this is where I want to stay.”

He is now one of a very small group of All Blacks including new captain Keiran Read who are in the mix to chase a third straight World Cup title, having also played in the 2011 home World Cup win.

Hansen described Williams as freakish athlete and one of the best, if not the best, in his position at inside centre.

“We saw that in the Rugby World Cup,” Hansen said.

“He made a difference every time he played and he allowed us to have a one-two-three punch.”

Hansen believed Williams’ involvement in New Zealand rugby sevens campaign this year ahead of the Rio Olympics would only enhance his development in 15s.

“I think by the time he is finished, he will be one of the greats of the game,” he said.

As for his departure from one-year contracts, Williams said he felt his rugby reached a different level at the World Cup and he now wanted to see how far he could go.

He is expect to join up with the All Blacks for the Rugby Championship after the Rio Games in August.

Next year, rather than rejoining the Chiefs, whom he helped to win the Super Rugby title in 2012, he will be moving north to Auckland to play for the perennially under-performing Blues.

It means a reunion with Blues mentor Tana Umaga, who was his coach at French club Toulon when he first switched from rugby league eight years ago.

Williams, who was born and raised in Auckland, says it was a tough decision to turn his back on the Chiefs, for whom he also played last season.

But he and wife Alana have a one-year-old daughter and are looking to have more children.

“My wife doesn’t have any family here and most of my family is in Auckland,” he said.

“I’m an Auckland kid and it’s pretty much home to me. That weighed a lot in my decision, and there’s no secret me and Tana go way back.”

Williams has played 33 Tests for the All Blacks. Between the past two World Cups he went back to rugby league in the NRL, gaining a premiership with the Sydney Roosters.