The Wallabies will need to "front-up" when they face a massive physical challenge from a seasoned Irish side at the Telstra Dome in Melbourne on Saturday.

New Wallaby coach Robbie Deans admitted on Wednesday, in revealing his new-look side, that the Irish will pose a major threat to his charges in what is Australia's first Test since the World Cup last year.

According to Deans his team will be somewhat underdone for the first of their 15 Tests of the year.

They have had less than two weeks together as a squad with their new coach, who arrived at the training camp only last Monday, and the side also includes several new faces.

Ireland, on the other hand, have played six Tests already this year: the Six Nations championship plus last week's torrid 11-21 defeat in New Zealand.

Deans made suggested that the Irish will have the edge in terms of match preparation.

"I was pretty impressed actually with the Irish (against the All Blacks), particularly their physicality," the Wallaby coach told AAP.

"They've developed some frames over the last few years. They're a group that's played a lot of rugby together and particularly in their respective units of up front and out the back.

"They bring with them a lot of mentality, if you like, and it's their last game before a break so they're going to bring everything they've got and they're going to throw everything at us.

"They were pretty impressive around the contact last week and they would also be pretty frustrated by the fact they weren't able to close that gate when it was possibly there to be done.

"So they'll be looking to do that this weekend."

Deans said his selection of Reds firebrand James Horwill in the second row ahead of in-form Waratah lock Dean Mumm was to give the Wallabies pack added aggression to combat Ireland's physicality.

"Yeah, James has got that potential in him, there's no doubt, and we're going to need that from everyone," Deans told AAP.

"We won't be able to back off the physical confrontation and hope to succeed. "We're going to have to engage Ireland somewhere and we're going to have to do well in that engagement if we're to hope to get home.

"For some (Wallabies), we're going from close to a month since they played rugby at all into a Test match - that's a big step.

"That's a big adjustment. You can talk it all you like but the reality of adapting physically is significant, so that's the first hurdle we've got to overcome."

365