Robertson went down early on Friday morning during the team’s last on-field session in Buenos Aires before they head to Salta to play the Pumas.
If the non-contact injury is as bad as first feared, Robertson is expected to spend an extended spell on the sidelines.
If confirmed to be an ACL tear, the injury may rule the 24-year-old out of World Cup contention, with the tournament less than one year away.
“I’d say he’s done a significant knee injury,” Wallabies coach Michael Cheika told reporters. “I won’t pre-empt scans or anything like that but it’s not looking ideal.”
“It was nothing. Just a very innocuous event, no contact, nothing. It looks significant.
“He’ll stay with us now, there’s no point sending him home yet, and when he gets home he’ll get the scans he needs and then I’d imagine, the operation he needs after that.”
Robertson hasn’t started for the Wallabies since the first Bledisloe Cup Test in Sydney, and has been left out of Michael Cheika’s matchday 23 for Australia’s last two fixtures.
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