The Brumbies have today confirmed Connal McInerey suffered a broken fibula in the side's win over the Melbourne Rebels on Saturday night.
The hooker left the field in the 8th minute and will undergo surgery tomorrow and is expected to be ruled out for an extended period.
Fellow front rower, James Slipper sustained an MCL strain in training last week and is expected to miss a further 3-5 weeks.
Meanwhile captain Allan Alaalatoa has been suspended for three weeks after receiving a red card in the 40th minute on Saturday night, the first of his career.
He will next be available for selection when the side take on the Queensland Reds on April 10 at Suncorp Stadium in Brisbane.
Brumbies coach Dan McKellar said: "It's really disappointing for Connal, he's the sort of player that puts his body on the line week in week out and has been playing some great rugby."
"While it's hard to replace players of the calibre of James and Allan, we pride ourselves on having a full squad mentality and we'll be calling on that this weekend in the Grand Final replay against the Reds."