Australia flanker Scott Fardy has been ruled out of Saturday's Test with Italy in Turin due to concussion suffered in last weekend's loss to England.
Fardy was knocked out cold after making a tackle on England full-back Mike Brown early in the second half and was carted off the field.
Wallabies coach Ewen McKenzie said that although Fardy was standing up and walking around qafter the end of the match, protocol would govern his return to play and he would be unavailable for selection this weekend.
"You've got to do a graduated training week, by the time you get through all that you really haven't done much preparation," McKenzie told the Sydney Morning Herald.
"So we've basically made the decision not to include him in selection for this week."
There was better news regarding the fitness of hooker Tatafu Polota-Nau, however. The 28-year-old, who has been sidelined for almost six months with a hamstring injury, is set to return via the bench against Italy after training with the side on Monday.
Polota-Nau's return will be a boost for the Wallabies as he has been sorely missed at Test level. He was the Wallabies' first-choice number two before his injury and during his absence Stephen Moore has started every Test this season, with Saia Fainga'a providing back up on the bench.
"He's pretty close, certainly close enough to be thought about, which is where we're at at the moment," McKenzie said of Polota-Nau.
"A lot of it is confidence after being a long while out of the game - having the confidence to get out there, especially with a hamstring, and doing all the things you need to do: scrum, bend over at the rucks and get cleaned out, and stuff like that.
"He's in a much better space. We did a lot of contact last week so he enjoyed that and it gives him confidence. He should be in the mix."
Fardy's injury is likely to result in a recall to the starting XV for Ben McCalman at number eight with Ben Mowen shifting to the blindside flank.
McKenzie is hopeful Fardy would be fit for the clash with Ireland on November 16.
"He's a pretty good campaigner, he's new on the Test scene but he's got a good instinct for the game,"McKenzie added.
"He's a good talker, which is what you need, he brings good energy to different situations, so it's disappointing."