New Zealand will unleash the raw power of Sonny Bill Williams on England on Saturday as the All Blacks prepare for a bone-shuddering collision with their northern hemisphere rivals at Twickenham.

Rugby league convert Williams was one of four changes from the All Blacks side beaten by Australia in Hong Kong last week, and will form a physically imposing partnership with Ma'a Nonu at centre.

New Zealand coach Graham Henry said Thursday the 1.93m, 108kg centre was being handed a Test debut in the expectation of a "hell of a physical contest" with England.

Williams's debut will cap a meteoric rise through the rugby union ranks following his transition from rugby league two years ago.

The 25-year-old turned down a reported offer of $US6 million ($A5.98 million) from French club Toulon in order to return to New Zealand and pursue his dream of playing Test rugby for the All Blacks.

Henry said he had first spoken with Williams about the possibility of playing for New Zealand when he was playing for Toulon last year.

"I rang him when we played France last year. He said to me 'I'd like to play for the All Blacks but I'll only come back to New Zealand if you think I'm good enough,'" Henry revealed. "He's that sort of person."

The softly-spoken Williams meanwhile admitted he was still pinching himself at his elevation to the All Blacks starting line-up.

"I'm still buzzing. It probably won't sink in until I run out there in front of 80,000 people on Saturday," Williams told reporters on Thursday.

"Couple of years ago it just seemed so far away. It's an unreal feeling to be not only in the team this week but starting. It's going to be massive."

New Zealand will also have an intimidating presence on the wing with Hosea Gear replacing the injured Cory Jane.

Henry said Gear had got the nod after mounting calls for him to be given a Test start for the All Blacks.

"Even my mother asked me why he's not in the All Blacks. My wife said I should pick him as well. So it was a foregone conclusion," he joked.

The other changes see Blues scrum-half Alby Mathewson replace Jimmy Cowan while Sam Whitelock comes in for Tom Donnelly at lock.

Henry said the 24-year-old Mathewson had been selected to see how he fared under pressure.

"We wanted to see how he could handle Test match rugby," Henry said. "Playing at Twickenham is a huge atmosphere, 83,000 capacity - it doesn't get much bigger than that. We just wanted to see how he would handle the situation and how other teams would handle him."

New Zealand

Mils Muliaina; Joe Rokocoko, Sonny Bill Williams, Ma'a Nonu, Hosea Gear; Dan Carter, Alby Mathewson; Kieran Read, Richie McCaw (capt), Jerome Kaino; Sam Whitelock, Brad Thorn; Owen Franks, Keven Mealamu, Tony Woodcock. Res: Hika Elliot, Ben Franks, Anthony Boric, Liam Messam, Andy Ellis, Stephen Donald, Isaia Toeava.

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