Leuenberger, 20, limped to the bench in the third minute of the 33-point win over the Sydney Swans and, despite returning to the field to play out the match, will have scans on his left knee on Monday to determine the extent of the damage.
"They think it might be the lateral meniscus," Lions coach Michael Voss told Melbourne radio station Triple M on Sunday.
"The best case scenario is he's just pinched it. I guess the worst case scenario is that he's torn it badly and they'll have to repair it so it might be three months. We're sort of hoping that it only just needs a little clean up which will be about four weeks.
"He's pulled up quite well [today]. He couldn't really lock out his knee last night, but this morning he can. We're obviously hoping that that's good news and that it's not too bad."
Leuenberger has played 22 games since the club snared him with the fourth overall pick at the 2006 NAB AFL Draft, but was ruled out of the final seven matches of last season with a knee complaint.
The injury is ill-timed for the Lions who are struggling to get lead ruckman Jamie Charman match fit in the AFLQ competition.
"Charmo really put in an effort for us to come up for round one, but you always knew he was going to be short of a gallop," Voss said.
"The last couple of weeks he's just probably needed to go back and get some time in. We were in a position where we felt we could do that and he went back and played quite well.
"Based on what's happened with Leuenberger he might come back in quite quickly."
