Captain James Horwill and star back Kurtley Beale have been ruled out of Australia's Tests next month against Scotland and Wales with injuries, coach Robbie Deans said on Monday.
Lock Horwill damaged his hamstring during the Queensland Reds' 13-12 Super 15 win over the ACT Brumbies on Saturday and scans Monday revealed a muscle tear.
Deans said the injury will keep Horwill out of the Test against Scotland in Newcastle on June 5 and the following three-Test series with Wales.
Beale injured his shoulder playing for the Melbourne Rebels in their 66-24 loss to the Hurricanes in Wellington on Saturday and scans showed he would also play no part in next month's Tests.
Beale had been favoured to start at fly-half for the Wallabies as the regular number 10 Quade Cooper continues to work his way back from a long spell out with a knee injury.
"Kurtley had an appointment this morning with a specialist. He's going to require an operation," Deans said, adding that the full extent of the damage to Beale's shoulder would not be known until after surgery.
The Rebels said Beale had undergone surgery to clean out floating cartilage from his left shoulder joint.
"Beale will be closely monitored over the coming days, but the initial assessment is that he will be unavailable for the next three to four weeks," the club statement said.
Deans said Horwill's injury was not as serious as he first feared.
"James, we are presuming, is out for the whole of June, but it is not as bad as it first looked. It looked pretty sinister at the time," Deans said.
Deans said he was not ready yet to announce his replacement captain, but flanker David Pocock and scrum-half Will Genia are considered front-runners to take the role against Scotland.