Taniela Tupou is returning to Australia for further scans on his suspected ruptured Achilles tendon, among six Wallabies players departing before their final Test against Wales.
With a minimum nine-month recovery from surgery, confirmation of the injury would put Tupou's participation at next year's World Cup in France in grave doubt in a massive blow to Australia's chances of success.
The hulking prop was one of five players forced off during their 13-10 loss to world No.1 Ireland in Dublin.
Untouched, he fell to the ground clutching his leg as he attempted to cart the ball up and was stretchered off.
The Wallabies announced early Monday that the injured players would fly home to Australia for further treatment, missing their Welsh clash this weekend.
Hunter Paisami suffered medial ligament damage in the opening minutes, leaving Australia without a specialist inside centre for the Cardiff Test.
Outside back Andrew Kellaway (toe) and No.8 Rob Valetini (ankle) were forced off during the second half against the Irish while hooker Dave Porecki was concussed.
Halfback Nic White also suffered a head knock but surprisingly passed his HIA to return to the field, however he too has been ruled out and will join the travelling wounded.
Tupou is the fourth Wallabies player to suffer a ruptured Achilles tendon this year following five-eighth Quade Cooper and forwards Harry Johnson-Holmes and Rob Leota.
However coach Dave Rennie insists the injuries are down to bad luck and the perils of a collision sport.
"Porecki got a shoulder to the head, that's bad luck, I'm not even sure how or what Kells (Kellaway) has done," Rennie said post match.
"It's a collision sport and they're collision injuries."
Lock Will Skelton and five-eighth Bernard Foley are unavailable for the Wales match as it falls outside the international window.
Rennie said he would call on a number of players who took part in their historic loss to Italy.
"We'll have to go into the depth of the squad again," Rennie said.
"I can guarantee there will be guys itching for another opportunity after the Italy effort."