Wallabies coach Rennie hails Hooper's courage after withdrawal

Australia coach Dave Rennie praised captain Michael Hooper for his courage after the flanker withdrew from the Wallabies' squad on the eve of their two-test Rugby Championship series in Argentina.

Hooper had been selected to play in Saturday's opening clash with the Pumas in Mendoza, but informed management on Friday he was not in the right frame of mind to play and has since departed the team's base.

"(There was) nothing that was evident to us, how he trained and how he contributed around the team, around leadership was excellent but clearly he's been struggling a bit and masking that pretty well," Rennie told reporters.

"But it came to a head last night and he was brave enough to call Sharon (Flahive, Wallabies team doctor) and have a chat with her and then involved (team manager) Chris Webb and myself to get an understanding of where he is at.

"The concern is all around his welfare and it was an easy decision to let him go home where he'll get plenty of support around him."

Hooper will return to Australia accompanied by his New South Wales Waratahs team mate Dave Porecki, who was already ruled out of both tests against Argentina after sustaining a head injury in training.

"We're not putting any time frames on it," Rennie said when asked how long Hooper would be sidelined.

"Obviously he's felt he's been able to suppress things over the past handful of weeks so we certainly weren't aware of anything," Rennie added.

Prop James Slipper, who has played 110 times for Australia, will captain the Wallabies in Hooper's absence while Fraser McReight takes over at the number seven position.

"It's not uncommon in life is it?" Rennie said of Hooper's issues. "(Rugby's) a cross-section of society. Often men will say bugger all and suffer