"I think New Zealand peaked 18 months ago when they played the British Lions," he explained.
"They have not played as well since that time and I think they are starting to worry.
"They have done everything they possibly can to win this World Cup.
"They expected to get out there and smash everyone in the Tri-Nations and I think they are asking themselves questions (like) 'my God, what's going on?'
"They've got a really tough (World Cup) draw and New Zealand won't win through to the semi-finals."
Ex-Wallabies coach Rod Macqueen, who guided Australia to the 1999 World Cup, agrees with Kearns, and claims the World Cup favourites have already shown their hand.
"One of their Achilles heels is do they have a Plan B or a Plan C?" Macqueen asked.
"I haven't seen a lot of that. I've only seen them play one way. They seem to be playing the same way."
And Macqueen thinks the team that could knock the all-conquering Kiwi line-up out of the World Cup is the Wallabies, who New Zealand are likely to meet in the semi-final phase of the showcase competition.
"The great competitive advantage Australia has got is they've got a very strong mind over the New Zealanders," he said.
"I think if anyone can beat New Zealand in the semis, it's this Australian team.
"They're not sacred. They've already beaten them once this year. I think they should have enormous confidence."
Australia begin their World Cup campaign against Japan in Lyon on September 8.