England, South Africa, France and others are not the All Blacks' biggest hurdle at the World Cup - controversial referee Wayne Barnes is.
That's the verdict of former All Black No8 turned television pundit Murray Mexted.
Asked by global rugby website Scrum.com to nominate New Zealand's toughest obstacle if they are to successfully defend the Webb Ellis Cup, Mexted replied: "Wayne Barnes" before adding he was not "bloody joking".
"I would very much hate to get Wayne Barnes at Cardiff against France - and that's a possibility," Mexted said of a potential New Zealand-France quarter final in Cardiff at the same venue where the All Blacks tumbled out of the 2007 World Cup on the back of a massively controversial performance by Englishman Barnes.
"It could happen yet; those referee associations can be funny buggers sometimes," Mexted said of Barnes' possible appointment to the match.
Scrum.com wrote that Mexted's view showed New Zealanders still haven't forgiven Barnes despite a general acceptance that he has improved markedly as a whistle-blower since that game and that the All Blacks were as much at fault for the defeat.
Asked about New Zealand's other obstacles beyond Barnes, Mexted tipped the Springboks, Wallabies and England as New Zealand's toughest opposition.
"And the reason I haven't included Ireland in that group, even though they are rated No.2 in the world, is that I don't think they can create anywhere near as many scoring opportunities. And I'd like to think that this World Cup, where rugby's matured so much in the last four years, will be all about teams who have the ability to create and score. And I see Ireland as being one step behind."
Mexted said the All Blacks had learned valuable lessons from their only defeat so far this year against Australia.
"I was surprised [at how far off the pace the All Black forwards looked], and it wasn't the same in Auckland. I don't know that Victor Vito did make the difference; I think it was more the speed of the ball.
"In Sydney, I thought the Australian scrum had an edge, and also at the breakdown; but a lot of the ball New Zealand was getting was slow, and therefore, you're starting from a disadvantage. If your backs are running forward onto the ball, and your loose forwards are half good, you'll win that tackle area.
"I don't think the scrum will be inferior. We've never had a problem in Europe with our scrum, with these same front-row forwards. We haven't had trouble against South Africa, either, or Argentina. I can't see that being a weakness. But I'm sure that experience in Sydney shook them up. It gave them a wake-up call."