The 19-year old reportedly suffered the injury at a Lions practice.
“They played a bit of match practice and Connor did his ACL so that’s really disappointing for him,” Brisbane’s high performance manager Damien Austin told AFL Media.
“He’s been really positive and will have an operation this week.”
Defender Marcus Adams is set to be sidelined for another two months after reinjuring his foot. It is the same foot Adams had surgery on during the league shutdown.
“We did a bit of investigation and that’s going to take a little bit longer than we thought, so he might be another six to eight weeks just to let that settle,” Austin said.
In positive news, skipper Dayne Zorko has been cleared to return this week from a calf injury.
“If a spot becomes available, the boys are going pretty well at the moment, hopefully I can slide back in,” Zorko told the club website.
Brisbane face Geelong at the SCG on Thursday night at 7.40pm (AEST).