Sonny Bill Williams goes for the line during the All Blacks vs Tonga opening match.

Richard Kahui of the All Blacks runs with the ball.

Dan Carter lines up a kick during the New Zealand v Tonga match at Eden Park.

Sonny Bill Williams in action at NZ v Tonga opening game of the Rugby World Cup.

Owen Franks of the All Blacks evades a tackle from Sukanaivalu Hufanga of Tonga.

Sonny Bill Williams of the All Blacks is tackled by the Tongan defence.

Andrew Ma'ilei of Tonga is tackled by Dan Carter and Sonny Bill Williams of the All Blacks.

Ali Williams of the All Blacks and Joseph Tuineau of Tonga clash.

All Black blindside flanker Jerome Kaino During the All Blacks vs Tonga opening match of the Rugby World Cup.

Sonny Bill Williams of the All Blacks and Taniela Moa.

All Blacks coach Graham Henry felt Richard Kahui gave the "pretty complete" performance his side couldn't muster as New Zealand struggled their way past Tongan in the World Cup opener at Eden Park.

The All Blacks eventually won 41-10, thanks mainly to a stirring first half performance that evaporated into a very mixed effort in the second spell.

But amidst it all there was some pleasing aspects, none more so than the work of the back three which was an area of real examination going into this match.

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Kahui was the pick but fullback Israel Dagg and fellow wing Isaia Toeava weren't far behind.

Henry said it looked like Kahui's future at this tournament might be operating down the touchlines rather than in the centres.

"Every time he has played wing he has played very well and he played exceptionally well again tonight," Henry said of Kahui.

"He created and scored tries and he was good defensively under the high ball ... (a) pretty complete performance really.

Henry also felt Dagg played "pretty well". Like Kahui, the young No 15 ran in two tries in this six-try effort by the All Blacks.

"He is a threat," Henry said of Dagg although he felt he had taken a couple of wrong options late in the match. Henry put that down to Dagg's lack of activity in recent times as he has battled back from his lengthy thing injury.

Overall Henry wouldn't give his side much more than a five out of 10 score for this first-up performance, though he was sure they would be all the better for it.

"We scored some good tries, got maximum points and defended well. But we made too many mistakes and gave away too many penalties basically. There's a bit of work to be done."

The All Blacks gave away 13 penalties and made 12 handling errors to blot their performance that had started so promisingly.

Henry's theory on that was: "It's early in the tournament, a bit of tension. We have been waiting a long time for this and perhaps we weren't as free as we normally are."

But he noted that at the last ill-fated World Cup the All Blacks had won their early matches by plenty "and it didn't do us much good".

"So I think there is some positive stuff there, things to build on and we are looking forward to playing the next one (against Japan)."