Australia inside centre Christian Lealiifano has been ruled out of Saturday's Bledisloe Cup clash against New Zealand in Dunedin with an ankle injury.

The goal-kicking ace aggravated an existing problem early in the Wallabies' morale-boosting 54-17 win over Argentina in Rosario earlier this month and was unable to come back out for the second half.

He was expected to train with the squad in Sydney on Monday, but Australia coach Ewen McKenzie ruled the 26-year-old out in his press conference at the team hotel.

Blindside flanker Scott Fardy has already been sidelined with an eye injury inflicted by team-mate Quade Cooper against the Pumas.

"We'll obviously have a couple of changes in our group. Fardy's out and Lealiifano won't make the game either, so there's a couple of changes there and that means we've got to rethink what we're going to do," McKenzie said.

The coach confirmed both Fardy and Lealiifano would be available for the Wallabies' next Test against England on 2 November.

He admitted he was not prepared to risk further injury to Lealiifano ahead of next month's spring tour.

"Lealiifano's ankle is still swollen. He's had an ongoing problem for some time," McKenzie said.

"But the reality is the short-term pain is to rest him and get him back to as close to 100 per cent as possible so that the next five games he's playing at close to 100 per cent.

"We didn't want to push him through now and end up having to be forced to play six games at 80 per cent, which I don't think would be fair on him or the team."

Asked if Brumbies fly-half Matt Toomua was in contention for the number 12 jersey, McKenzie replied: "He's a definite possibility, yep."

Goal-kicking midfielder Mike Harris is another option after being named in an extended 32-man squad, while Ben McCalman and Dave Dennis are the candidates to replace Fardy in the number six jumper.

Meanwhile, McKenzie insisted he would not radically alter the Wallabies' tactics despite suffering consecutive losses - 47-29 and 27-16 - against the All Blacks in August.

"We've done good things in both those games so we can look at that but that said they're a very consistent team who have been advancing their game," he said.

"They've got some very strong bits and pieces to what they do. It'll be interesting to see how they pick their side and how they go about it, but we'll have a definite idea how we want to go about it.

"But tactically we'll have strong thoughts and some of those things worked well for us - we just didn't play the 80 minutes and weren't consistent across the 80 minutes, so our focus will be on doing that."