Interim coach Ron Rolston listed Vanek as day to day on Wednesday, a day after the player was hurt in a 3-2 overtime win at Montreal. Vanek did not return after being struck by a shot taken by teammate Christian Ehrhoff midway through the second period.
Rolston said Vanek was feeling little bit better, but his playing status will depend on how much pain he can tolerate. Vanek was spotted walking with a noticeable limp in a players' area outside the locker room Wednesday.
He leads Buffalo with 14 goals, 17 assists and 31 points.