The veteran right-winger said Monday that he first hurt the knee during the summer but it was feeling better until he collided with a Chicago Blackhawk early in the third period of Toronto's 6-4 home loss Saturday.
He had an MRI Sunday.
"There is slight damage to some ligaments," he said after emerging from the team's practice rink dressing room following treatment on the knee by training staff. "We don't know how extensive it is or how long is will take time-wise.
"As of now, it's indefinite. Hopefully, I'll get a brace made and we'll see how it progresses from there."
Surgery is not expected to be required, he said.
Tucker had one goal and four assists in the team's nine games.
He joins Kyle Wellwood (groin) and Carlo Colaiacovo (knee) on the injured list.
Coach Paul Maurice said Boyd Devereaux (back) has recovered sufficiently enough to return to the lineup Tuesday when the Atlanta Thrashers visit.