The Wallabies are still searching for their first win of the Rugby Championship after losing the Bledisloe Cup to New Zealand last month.

Five-eighth and fullback will be the two most contentious selections, as Quade Cooper and Israel Folau vie to take over from incumbents Toomua and Mogg.

But Larkham hopes Wallabies coach Ewen McKenzie gives the Brumbies' duo more time to settle into their Test roles.

''I thought [Toomua] didn't run the ball as much as he needed to [in the first Test] but we saw a dramatic transformation in the second Test; I thought he was outstanding,'' Larkham said.

''I think if this team's given more time together, they will start to string wins together.

''You've got to give [Mogg and Toomua] some time to find some combinations out there. [Toomua] is very well suited to Test rugby. 'Moggy' just needs a bit more time. Maybe he needs to run the ball a bit more, but his kicking was outstanding and so was his defence.''

The Wallabies went into camp on Sunday to prepare for the Springboks. Cooper and Folau are two of the highest-profile players in the team and their presence increases the spotlight on Mogg and Toomua.

There have been calls for McKenzie to shift Australian rookie of the year Folau from the wing to fullback to better utilise his attacking brilliance.

Mogg has been the fullback for the first two Tests and will meet with McKenzie this week to discuss how he can improve. Toomua and Cooper have been used in tandem as the Wallabies' chief playmaker.

Brumbies backs coach Larkham said the combination of Toomua's structured style and Cooper's enigmatic flair had ''tremendous potential''.

Toomua has been the starting No.10 for the Tests against the All Blacks but it remains unclear whether McKenzie will select Cooper in the starting XV for South Africa and Argentina.

The Brumbies have dominated the Test team to start the Rugby Championship after they made it to the Super Rugby grand final.

Prop Ben Alexander could be under pressure to keep his spot, while Scott Fardy impressed in his run-on debut against the All Blacks two weeks ago.

McKenzie also wants more impact from his bench players after they disappointed in the first two Tests. Mogg is hopeful of keeping his place in the starting XV and wants to show he belongs on the international stage.

But with McKenzie replacing Robbie Deans as coach in July and implementing a new game plan, Mogg said it would take time for the team to adjust.

''It hasn't been through a lack of trying, just execution a bit, and I'll improve at training and bring it into games,'' he said. ''We're going to get better with the more time we have together and keeping the combinations.''