Fly-half Dan Carter expects Argentina to pose a real threat to New Zealand in the opening game of their Rugby World Cup campaign.
The defending champions come face-to-face with the Pumas at Wembley on Sunday in their first Pool C clash in what looks to be their biggest test of the early stages.
It was the All Blacks who ran out 39-18 victors when the two sides met in the Rugby Championship in July, but Carter believes Argentina have improved since that win in Christchurch.
"It's going to be a really tough match first up," he said. "We played Argentina earlier in the year and they're quality opposition.
"We're wanting to start this tournament on the right note with the win but we'll have to play extremely well in order to do that.
"This will be completely different. The World Cup brings a whole new challenge.
"Argentina are going to be at the peak of their powers, they're going to be in good form and they had some good success against South Africa after we played them earlier in the year so they're going to come into this game with a lot of confidence."
Despite his concerns over Argentina, Carter is confident the All Blacks have prepared well and are ready to try and retain their title.
He added: "I've experienced a few different preparations and when you get to a World Cup, what you want to know is that you haven't left any stone unturned and you don't want to be looking back at what things you would have done differently.
"There's nothing that I can think of [that has been left out] so we're really happy with the preparation and have that excitement in the air and the whole squad are ready to get into it."