The Socceroos will be without defender Matthew Spiranovic for Australia's upcoming World Cup qualifiers against Kyrgyzstan and Bangladesh, officials said on Monday.
He has been battling a calf injury and was ruled out after being assessed by staff, Football Federation Australia said.
Coach Ange Postecoglou has decided not to replace Spiranovic in the squad which is gathering in Canberra ahead of Thursday's match against Kyrgyzstan and the November 17 tie against Bangladesh in Dhaka.
Australia are second in their qualifying group after losing 2-0 to Jordan last month, and dropping any more points would complicate the Socceroos' path to the 2018 World Cup.
Star player Tim Cahill said the defeat in Amman was a "wake-up call" for the Asian champions.
"We've lost one game in the handful of games that we've played -- it's not panic stations," he said.
"We had a wake-up call against Jordan, which is probably something we needed."
The Socceroos, who will have Mile Jedinak and goalkeeper Mat Ryan back after both were declared fit, are expecting Kyrgyzstan to be a tough opponent, Cahill said.
"We know we're going to be up against a tough one in Kyrgyzstan, whether we're playing at home or not," he said.
Australia are second in their group on nine points having played four games, behind Jordan on 13 after five.
The eight group winners and four best-placed runners-up will reach the next stage of qualifying.