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LONDON - If size really does matter, New Zealand's backs should have the edge against England at Twickenham.

Graham Henry has made four changes from the starting XV that lost to Australia in Hong Kong.

The most anticipated of those was at centre, where Sonny Bill Williams replaces Conrad Smith.

He will pair with Ma'a Nonu in forming a 212kg midfield partnership, surely the heaviest in All Black history.

The whole backline outside of Dan Carter looks physically imposing, with Williams the top weight at 108kg and Mils Muliaina (93kg) the only one not to crack three figures.

Given that England also have a huge backline, with centre pairing Shontayne Hape and Mike Tindall pushing the scales out to 102kg, it's almost a case of anything you can do, we can do bigger.

In other changes, Sam Whitelock will play his 10th test, but his first with a single-digit number on his back as he comes in for Tom Donnelly.

Alby Mathewson also gets his first start, with Jimmy Cowan rested and Hosea Gear will start a test for the first time in more than two years.

He will occupy the left wing while Rokocoko shifts to the right to replace the injured Cory Jane.

Ben Franks, Anthony Boric, Liam Messam and Andy Ellis come on to the bench alongside hooker Hika Elliot and under-fire duo Stephen Donald and Isaia Toeava.

There will be plenty of interest to see whether Gear, 26, can translate his outstanding form for the Maori, Wellington and sevens sides to the test arena.

Just two tests have pock-marked the winger's career, an unsatisfactory start against Australia in Hong Kong two years ago and a 20-minute cameo off the bench against the same side in Wellington last year.

"I'm thankful I've given another opportunity and want to make the most of that."

Gear could not help feel disappointed and wondered if his international window had passed him by when he was overlooked for the Tri-Nations, despite a stellar outing for the Maori in their three-match centenary series that included wins against Ireland and England.

The communication he received was that few doubted his finishing skills, but question marks remained over his error rate and, most importantly, his work rate.

"They wanted to see me getting my hands on the ball, getting a few more touches and getting involved," Gear said.

The Gisborne-born flyer has strong motivation to do well at Twickenham.

He knows he has yet to do his talent justice in an All Black jersey and with a clutch of talented outsides including Israel Dagg, Zac Guildford and Rene Ranger not on tour, a poor performance could be his final performance.

"I've probably got to look at it as if it could be my last game in a black jersey and make the most of it," he said. "I don't want it to be the last; never want it to be the last."