Australia's injuries woes worsened on Monday with confirmation that captain James Horwill will miss all the June internationals and the revelation that star back Kurtley Beale will have to undergo surgery.
Australia face Scotland and Wales next month.
Lock Horwill damaged his hamstring during the Reds' 13-12 Super Rugby win over the Brumbies at the weekend 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 (on June 9, 16 and 23).
Beale injured his shoulder playing for the Rebels in their 24-66 loss to the Hurricanes in Wellington and scans showed he would also play no part in next month's Tests.
Beale had been favoured to start at flyhalf for the Wallabies as the regular No.10 Quade Cooper continues to work his way back from a long spell out with a knee injury.
"Kurtley had an appointment this [Monday] 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.
"But the fact that he needs an operation is indicative of the fact that it is serious and it will rule him out of the June [Test] window."
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 flank David Pocock and scrumhalf Will Genia are considered front-runners to take the role against Scotland.
Despite the injury, the skipper had joined up with the Australia squad and coaching staff in Sydney.
With a final round of Super Rugby games to be played before the international break, Deans will name his team on Sunday for the Scotland Test next Tuesday.
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