Wallabies scrum-half Will Genia has been dropped for Australia's crucial Rugby Championship clash against Argentina on Saturday with Ben Mowen taking over the captaincy.

Genia is considered to be one of the best halfbacks in world rugby but has struggled for consistency and paid the price for last weekend's 38-12 drubbing at the hands of South Africa in Brisbane.

He drops to the bench for the must-win match against the Pumas in Perth, with Nic White replacing him in the starting line-up.

With James Horwill out injured, Genia has been the stand-in skipper, and that role now falls to Mowen, who only made his Test debut in June against the British and Irish Lions.

Coach Ewen McKenzie, who has suffered three defeats in a row since taking over from Robbie Deans and finds himself under increasing pressure to notch his first win, said it was tough to bench Genia.

"The fact that Will has captained his country shows what high regard we hold him in, and while he is naturally disappointed, I also know how competitive he is and I've got no doubts he will train himself to a standstill to bounce back as a better player," McKenzie said.

"We've spoken about what areas we believe he can continue to improve and evolve his game and he was receptive to going back and addressing those things.

"In the end, it wasn't an easy decision because he is undoubtedly a world-class player."

McKenzie said White was a worthy replacement and would add "his own uniqueness and point of difference to how we want to play this game".

"Nic has had a great season with the Brumbies and has brought his own brand of energy and hard work to the Wallaby group," he said.

"We've all been impressed by the contributions he has made to the team and in training, and we now look forward to seeing him bring his skills to the fore of the pressure-cooker on Saturday night."

Elsewhere, Quade Cooper is retained at flyhalf, with Israel Folau again named at fullback.

Prop Ben Alexander replaces Sekope Kepu in the front row after the Wallabies were smashed in the scrum by South Africa last week.

Since McKenzie took over, the Wallabies have conceded a total of 12 tries in two losses to the All Blacks and one to the Springboks, and must win in Perth to avoid a fifth straight loss -- a run not seen since Eddie Jones's ill-fated final year in charge in 2005.

"Rugby is a game of chess and we will look forward to the challenge of getting the right balance and our first Rugby Championship win," the coach said.

Australia (15-1)

Israel Folau, James O'Connor, Adam Ashley-Cooper, Christian Lealiifano, Nick Cummins, Quade Cooper, Nic White, Ben Mowen (capt), Michael Hooper, Scott Fardy, Kane Douglas, Rob Simmons, Ben Alexander, Stephen Moore, James Slipper

Replacements: Saia Faingaa, Scott Sio, Sekope Kepu, Sitaleki Timani, Ben McCalman, Will Genia, Matt Toomua, Tevita Kuridrani