A shoulder injury has ruled Ben McCalman out of Australia's forthcoming Rugby Championship encounters with South Africa and Argentina.
McCalman fractured his right shoulder blade as the Wallabies suffered a 23-7 loss in the second Test against Australia in June, but returned to international action in the 42-8 defeat to New Zealand on August 20.
The 47-times capped back-rower joins an increasingly lengthy list of absentees for Michael Cheika, with Matt Giteau out due to an ankle injury and Adam Ashley-Cooper returning to Bordeaux-Begles.
Rob Horne also drops out of the squad due to a shoulder injury and Matt Toomua will be missing after suffering a concussion.
Luke Morahan, Henry Speight and Rory Arnold, as well as uncapped duo Kyle Godwin and Sefa Naivalu - who will not become eligible for selection until after the two Tests - have been called up as replacements for the quintet.
Following defeats in their opening two matches against New Zealand, Australia will be looking to get off the mark when face South Africa in Brisbane on September 10 before moving on to Perth to entertain Argentina one week later.