Coach Dave Rennie has saluted the courage of Australian captain Michael Hooper, who on Friday pulled out of the Rugby Championship Test against Argentina to protect his mental wellbeing.
Veteran flanker Hooper will fly home from Mendoza after telling Wallabies teammates he lacks the necessary "mindset" to play for his country, let alone lead them, in Saturday's Test.
Prop James Slipper, a fellow-Test centurion, will take over as captain while Fraser McReight is promoted to replace Hooper at openside flanker.
A Rugby Australia statement said Hooper had addressed the team and expressed the "utmost confidence" they could win the Test against the Pumas without him.
"While this decision did not come easily, I know it is the right one for me and the team at this point in time," the 30-year-old said.
"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."
Rennie told Australian media Hooper's decision and actions were courageous.
"He is such a professional, he was able to get on and do the job. He addressed the team today, which took an enormous amount of courage, and let them know he's not OK, and he thought it was best for himself and best for the team that he heads home," Rennie said.
"It's not uncommon in life is it? It’s a cross-section of society and often men will say bugger all and suffer in silence.
"He has a huge amount of respect from everyone, and we want to get him home and get him as much support as we can."
Rennie said Hooper had hidden his internal issues for several weeks and marvelled that the 121-Test veteran continued leading the side while unwell.
Hooper had acknowledged his vulnerabilities through personal conversations with team doctor Sharron Flahive, manager Chris Webb and Rennie.
"Clearly he has been struggling a bit and masking that pretty well," Rennie said.
"It came to a head last night and he was brave enough to call Sharron and have a chat with her and then (manager) Chris Webb and myself, to get an understanding of where he is at.
"He has been able to suppress things over the last couple of weeks, and we certainly weren't aware of anything."
Australia face Argentina again next week in San Juan before a week's break, followed by two Rugby Championship Tests at home against South Africa.
Rugby Australia chief executive Andy Marinos said Hooper's health takes priority and no pressure would be placed on him to return to action.
"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," Marinos said in a statement.
"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."
Hooper has built his reputation on durability, having become the fastest player in Test history to reach 100 caps, despite playing in a physically demanding position.
He has missed remarkably few matches, a trademark also of his Super Rugby career at both the ACT Brumbies and New South Wales Waratahs.
Hooper added to his schedule by playing a short club stint in Japan late last year.
Slipper, 33, has been captain of the Wallabies once before in his 112-Test career, when they beat the United States in Chicago in 2015.