All Blacks coach Graham Henry gave his team a bare pass mark after they battled their way to beating Tonga 41-10 in the Rugby World Cup opener.

After racing to a 29-0 lead in the first half hour, the All Blacks allowed Tonga back into the game with the margin narrowing to 34-10 before they scored a late try.

The top-ranked All Blacks went into the match wanting to make an emphatic statement that they were on top of their game but instead produced their lowest ever score against the lowly rated Pacific Islanders.

Henry said he rated his side’s performance at “six or so” out of 10, particularly because of how they fell away in the second half.

“We scored some good tries, got maximum points, defended well, had a good structure, made too many mistakes and gave away too many penalties so a bit of work to be done,” he said in summing up the performance.

With rugby-obsessed New Zealanders demanding their side atone at their home World Cup for repeated failures over the past 24 years, captain Richie McCaw tried to put a positive spin on the unconvincing performance.

“There were some good things, particularly early in the game, things we practised came off but it’s a pity we didn’t do it for the whole 80 (minutes),” he said.

“We had two or three opportunities to score and we didn’t do that and we probably got a bit frustrated trying to achieve a bit much and we made mistakes.”

Henry was also angered by the way the Tongans opted for scrums on the All Blacks line in the second half, looking for a try when a penalty was on offer.

It sent a message to tournament heavyweights Australia, South Africa, France and England that they did not rate the All Blacks pack as a weapon to be feared, but Henry believed it ruined the game.

“I don’t think anyone enjoyed it to be frank, pretty boring part of the game,” he said.

“I’m sure the people who were watching it live and on tv would agree with that, so the less repeats we have of that in the tournament the better.”

Tonga replacement prop and try scorer Alisona Taumalolo, however, rated the scrums as the best part of the game.

“I really enjoyed it. I loved it. I kept saying to the ref I can scrum all night.

“We showed the world we can scrum, and we love contact and a physical type of game. For us we took a chance and scrummed with one of the best scrums in the world and I was excited.”

Taumalolo gave credit for the technique of the Tonga scrum to their specialist coach Dan Cron, a son of the All Blacks scrum coach Mike Cron.