He's the heir apparent to injured All Blacks maestro Dan Carter - but Hurricanes young-gun Aaron Cruden insists he won't be out to impersonate the world's best flyhalf when he makes his run-on debut against the Wallabies in Sydney on Saturday night.

While the All Blacks won't confirm their line-up for the Bledisloe Cup clash until Thursday, the 21-year-old has been guaranteed Carter's No.10 jumper for the Sydney Test as the veteran recovers from recent ankle surgery.

And while the 2009 IRB Junior Player of the Year is desperate to impress this weekend, he is determined not to overplay his hand against the resurgent Wallabies.

"I'm definitely stepping into some big shoes and I believe he (Carter) is the best five-eighth in the world, but I think it is important for me just to go out there and play my natural game and do what I can that's going to be beneficial for the team," Cruden said on Tuesday.

"And I'm pretty keen to go out there and do that."

"Obviously I'm not going to be Dan Carter I'm going to be Aaron Cruden, and we're going to do things differently."

"But I think the game plan we've got set doesn't change a hell of a lot from my natural game and I'm pretty keen to go out there and show my wares."

Skipper Richie McCaw backed Cruden to make the most of his opportunity.

"He's had a couple of weeks to think about it and he's got a bit of confidence and we've got to make sure we help him but just allow him to do what he can do and I'm sure he'll have a good one," McCaw said.

Cruden, who was diagnosed with testicular cancer in 2008 which necessitated the removal of one of his testicles, made his belated Super 14 debut with the Hurricanes this season.

His elevation to the Hurricanes starting line-up mid season coincided with their late charge towards the finals, and he has subsequently earned five Test caps off the bench.

But while he knows he faces a massive step up in his first Test start, the presence of Hurricanes team-mates Piri Weepu, Ma'a Nonu, Conrad Smith and Corey Jane, who are all expected to be named in the starting side, will make his job a lot easier.

"It'll give me a lot of confidence and it'll just make me feel a lot more comfortable out there," he said.

"I think to see familiar faces and guys that I've got an understanding with and combination with. So if that is to be the starting line-up then it's going to be pretty special."

But the 79kg flyhalf knows the Wallabies won't be quite so welcoming, as they look to exploit his at times suspect defence at ANZ Stadium.

"I definitely think so," he said when asked if he is expecting to be heavily tested in defence.

"They targeted Dan quite a lot in Christchurch as well down his channel so I don't see why they wouldn't do the same."

"I've been putting in a few hours of work on defence and it's going to be a huge challenge but one I'm pretty keen to test myself in."

The confident youngster also expressed his desire to assume the goal-kicking responsibilities, insisting he's 'pretty confident' he would be up to the task if required.