All Blacks have to scrummage for two

The All Blacks must help seriously weaker opposition scrums stay up to avoid getting the blame for collapses, according to New Zealand assistant coach Mike Cron.

Cron, a renowned "scrum doctor", said the New Zealand forwards were "ticking along" in the set piece, to the extent he felt their dominance had led them to be harshly penalised by referees on occasion at RWC 2011.

"We have probably been guilty earlier in the campaign of being just a fraction too aggressive and it ends up in a collapse and it ends up in a penalty against you," Cron said on Wednesday. "So we've got to be smarter, which I think we will be."

He said his forwards enjoyed playing against France last weekend because they provided a proper contest in the engine room.

"The hardest thing for a front row to go against is a weak prop. We all hate it. It's the hardest thing to try to keep them up."

However, he added it was vital his All Blacks unit attempted to prevent the collapse of weaker opposition formations, for safety reasons as well as to avoid an unwarranted sanction.

Squeaky clean

"You've got a responsibility if you are so dominant over another team. You have a responsibility to keep things up, one for safety and the other is to stay in control of your movement.

"All we can control is what we can control and that is if we ensure we are squeaky clean, have great technique and take the decision-making out of the referee then we'll be fine."

Cron said he felt sympathy for referees who had to make decisions on scrum penalties in matches. He often had to consult the video at training sessions to see what had gone wrong because he was too close to the action to tell.

On balance, he felt the standard of scrummaging at RWC 2011 was better than in previous tournaments.

"I think most sides, particularly the minnows, I've been quite impressed with. Their technique is pretty good compared to a few years ago.

"Everyone's got a reasonably positive attitude I think to scrummaging.

"Unfortunately it's such an art that if one member is technically not quite sound it can end up with a lot of collapses or resets, which is frustrating for everyone."

New Zealand, who have already qualified for the quarter-finals, play their final Pool A match against Canada at Wellington Regional Stadium on Sunday afternoon.