Dave Rennie says captain Michael Hooper has shown "true courage" by withdrawing from Australia's Rugby Championship opener against Argentina.

The flanker opted against facing the Pumas at Estadio Malvinas Argentinas on Saturday, as he is not in the right frame of mind to play.

James Slipper will step in to lead the Wallabies in Mendonza, with Hooper heading home and Fraser McReight getting a late call to take the number seven shirt.

Australia head coach Rennie praised Hooper for making such a brave decision.

"Michael's one of the most professional and impressive men I've coached I know this has been a difficult decision for him," he said.

"He's shown true courage by acknowledging where he is at and acting on it.

"We will support him in any way we can and I know the team will be focused on getting the job done tomorrow."

Hooper said: "While this decision did not come easily I know it is the right one for me and the team at this point in time.

"My whole career I’ve looked to put the team first and I don't feel I am able to fulfil my responsibilities at the moment in my current mindset."

Rugby Australia CEO Andy Marinos says Hooper will be given all the support he needs.

He said: "Michael is an incredible leader, it takes a brave man to identify where he’s at and come forward whilst having the best interests of the team at heart.

"His wellbeing is and remains the highest priority right now where Rugby Australia and the Australian Rugby community will do everything to support him and his family."