Ewen McKenzie's selection of Kurtley Beale as Wallabies fly-half may have "dumbfounded" All Blacks coach Steve Hansen, but Ma'a Nonu expects a tough challenge.

Nonu doesn't expect to make easy ground through Beale and Matt Toomua in the Wallabies' 10 and 12 channels.

"They talk about Beale not being a great defensive player but I think he's worked hard in the last two years, and he's an attacking weapon," Nonu said. "We've seen him this year playing probably the best Super 15 he's ever played. We know Toomua's relatively a first-five playing second-five, but defensively he's pretty good."

Toomua, conversely, knows he'll have his work cut out containing Nonu.

Ma'a Nonu breaks tackles for fun © Getty Images

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"I've played Ma'a many, many times in Super Rugby," Toomua said of New Zealand's backline juggernaut.

"You actually cross him more when you're playing 10 than 12 because, quite often, you have that slide defence. I dare say I'm going to cross him again, but I could be crossing Ben Smith - there's threats all over the park. So I can't be focusing too much on one player, although he is someone who will keep my hands full."

Toomua said Beale would also have his hands full trying to stop Nonu, rejecting suggestions the fly-half would defend on the wing. "We've got full confidence in him defending in the frontline."

Both teams go into the game after winning all three of their June internationals, though the All Blacks were severely tested in their first two games against England.

"A lot of us took it for granted coming off Super Rugby, thinking it could just roll over and we could perform as All Blacks," Nonu said. "Preparation's got to be key in terms of hitting the line at eight o'clock in Sydney. We want our skills to be crisp, we want our physicality to be dominant, we want our minds to be ready for the game."

Nonu will be taking on the Wallabies for the 22nd time, but he says every Test brings a new challenge. "People may see it as just playing Australia again but for players it's not. They're always improving, we're always improving. We've just got to win more moments than them."