Fraser Gehrig suffers a calf strain in St Kilda's pre-season win over Geelong.
Gehrig's injury may prevent the forward from playing in the opening round of the 2008 regular season.
Saints coach Ross Lyon, however, was more optimistic.
"It looks like he has just strained a calf, so it is not ideal, but it won't affect him you wouldn't think for round one," Lyon said.