Sydney - The Wallabies are expected to have a new captain for next month's home Tests against Scotland and Wales as skipper James Horwill will likely be ruled out with a hamstring injury.
Horwill's name was missing when a 39-man training squad was announced by coach Robbie Deans on Sunday.
Horwill looked a disconsolate figure as he limped off early in the second half of the Reds' 13-12 Super Rugby victory over the Brumbies in Canberra on Saturday.
The giant lock will have scans on Monday and Reds coach Ewen McKenzie hinted the injury could mean several weeks on the sidelines.
"I don't think he'll be running out next week, put it that way," said McKenzie, who indicated the injury could be related to some earlier surgery on Horwill's hamstring.
"I'm not an expert but... maybe some scar tissue has given way. We're hoping for the best."
David Pocock and Will Genia are the leading contenders to take over as captain for Australia's Test against Scotland in Newcastle on June 5 followed by three internationals against Wales in Brisbane, Melbourne and Sydney.
The flyhalf spot is another area of concern for the Wallabies after Kurtley Beale injured his shoulder playing for the Rebels against the Hurricanes in Wellington on Saturday, although he was included in the training squad.
The injury doubt over Beale, coming on top of sidelined James O'Connor, has resulted in the selection of Quade Cooper, even though the Reds flyhalf has had just 120 minutes of playing time since recovering from a serious knee injury suffered at last year's World Cup in New Zealand.
Fourteen members of the extended training squad are yet to represent Australia in a Test match.
Deans said selectors will name Australia's match squad to play Scotland on June 3, two days before the Test match.
Deans said delaying the naming of the squad until after the final Super Rugby match featuring Australian teams in next weekend's round was imperative.
"We can't finalise a side for that match until all of the games are played, and we are in a position to assess all of the players," Deans said.
"Obviously we have preliminary ideas but the selection probably will change, as a result of events through the final round of Super Rugby before the international break."
Adam Ashley-Cooper (NSW Waratahs), Berrick
Barnes (NSW Waratahs), Kurtley Beale (Melbourne Rebels), Quade Cooper
(Queensland Reds), Anthony Faingaa (Queensland Reds), Bernard Foley (NSW
Waratahs), Will Genia (Queensland Reds), Michael Harris (Queensland
Reds), Rob Horne (NSW Waratahs), Digby Ioane (Queensland Reds), Pat
McCabe (ACT Brumbies), Jesse Mogg (ACT Brumbies), Luke Morahan
(Queensland Reds), Nick Phipps (Melbourne Rebels), Dominic Shipperley
(Queensland Reds), Joseph Tomane (ACT Brumbies), Cooper Vuna (Melbourne
Rebels), Nic White (ACT Brumbies).
Ben Alexander (ACT
Brumbies), Dave Dennis (NSW Waratahs), Kane Douglas (NSW Waratahs), Saia
Faingaa (Queensland Reds), Scott Higginbotham (Queensland Reds),
Michael Hooper (ACT Brumbies), Sekope Kepu (NSW Waratahs), Salesi Ma'afu
(Western Force), Ben McCalman (Western Force), Stephen Moore (ACT
Brumbies), Cadeyrn Neville (Melbourne Rebels), Dan Palmer (ACT
Brumbies), Wycliff Palu (NSW Waratahs), David Pocock (Western Force),
Tatafu Polota Nau (NSW Waratahs), Hugh Pyle (Melbourne Rebels), Benn
Robinson (NSW Waratahs), Nathan Sharpe (Western Force), Rob Simmons
(Queensland Reds), James Slipper (Queensland Reds), Sitaleki Timani (NSW