Sam Carter is awaiting the results of scans on his nasty-looking knee injury sustained on Friday against the Bulls.
The Australia international limped off during the Brumbies' 22-16 win despite trying to play on.
Carter won 11 caps for the Wallabies in 2014 and has been one of their most promising players in the pack, so the outcome of his scans will be eagerly awaited by both Michael Cheika and Stephen Larkham.
"I imagine he won't be playing next week," Larkham told reporters in the Australia capital.
"Like any test player, international player, it's going to be a loss to your team.
"He had a bit of a spell out of the game but I thought the last couple of weeks he's really played exceptionally well. But I think we're lucky we've got good experience in the second row with Blake Enever and Rory Arnold.
"I think those guys have gained enough experience throughout the year to be able to fill the shoes that Carts leaves."