Melbourne - The Wallabies suffered a major Test series blow against Ireland on Sunday with scrumhalf Will Genia ruled out with a broken arm.
The influential Genia broke his right arm in the first half of Ireland's series-levelling 26-21 win over the Australians in Melbourne on Saturday ahead of the third Test in Sydney later this week.
Genia was expected to undergo surgery on Sunday, likely also ending his Super Rugby season with the Melbourne Rebels.
But he may be back for Australia's Rugby Championship campaign against New Zealand, South Africa and Argentina.
Genia went off in the 27th minute with the arm fracture after running a decoy line in a lineout minutes earlier.
"We ran the play down the front (of the lineout) and Willy's the decoy around the back and he got king hit from the side," coach Michael Cheika said.
The Wallabies received better news on Sunday on key lock Adam Coleman, enabling him to re-join the Wallabies squad for the series decider against the Six Nations champions on Saturday.
Coleman came off just after half-time with a swollen cheek but scans cleared him of a facial fracture.
Nick Phipps is expected to start the Sydney Test in Genia's place after playing for the final 50 minutes in Melbourne and earning the praise of Ireland coach Joe Schmidt for a strong defensive effort.
"I thought Nick Phipps' tackle on Keith Earls was an absolute try-saver, I think it's a Nick Phipps special really," Schmidt said.
"He works so hard in the line, he's a very good cover defender and he did a great job."
A high penalty count, lack of possession and inconsistent kicking left Cheika frustrated by Saturday's loss.
"I don't know if we played good enough to go two-nil up," he said.
"I know we scored three tries to two but I just think we need to trust our systems a bit better... we gave away some 50-50s and we shouldn't have that doubt, and that will be a work-on for next week."