The knee injury to towering defender Harry Souttar has forced Socceroos coach Graham Arnold to make changes to his squad for next week's World Cup qualifier against China.
The Stoke defender underwent scans on Friday after being stretchered off in the second half of Thursday night's 0-0 draw with Saudi Arabia in Sydney.
The full extent of Souttar's injury is yet to be revealed with an ACL injury suspected.
Arnold indicated after the Saudi clash it wasn't looking good for the Scottish-born centre-back.
"It's very serious," Arnold said. "I'm really down and devastated for Harry.
"He's such a great kid. I believe he's the best centre-back in Asia.
"If it turns out to be a bad injury, it's not only a blow for Harry, then it's a blow for us."
With Souttar ruled out of the trip to the UAE to face China on Tuesday, defensive pair Ryan McGowan and Bailey Wright have been added to the squad.
McGowan is currently in Kuwait playing for 15-time national champions Kuwait Sporting Club while Wright is plying his trade in England's League One with Sunderland.
Melbourne City winger Andrew Nabbout, who came off the bench in Thursday's game, will not travel to the Middle East and has been released from the squad to rejoin the A-League Men champions ahead of their FFA Cup clash with South Melbourne later on Friday.
If Souttar's injury is as serious as feared it would not just be a setback for the Socceroos but also Stoke, who are chasing promotion in the English Championship.
In a glimpse of Arnold's thinking ahead of the game against China, Milos Degenek was deployed at the back after Souttar went off.
Australia seemed to lose focus after Souttar's departure and were reliant on Mat Ryan's reflexes to keep the Saudis at bay after dominating for most of the game.
"It got the boys down a bit and they see such a good guy going off on a stretcher," Arnold added.
"It probably, mentally, had a bit of an effect on them. After that we were a bit sloppy.
"It was two teams working hard and we both walked away with a point."
