The Bruins rallied for a 5-3 win that tied the series at 1.
Sabres coach Lindy Ruff wouldn't reveal the severity of the injury or whether Vanek would play Monday. Ruff would only say that he expects Vanek to travel to Boston with the team.
Vanek was injured after he was hooked from behind by Boston's Johnny Boychuk during a partial breakaway with less than seven minutes remaining in the opening period. After getting off a backhand shot, Vanek and Boychuk both fell and slid into the end boards.
Vanek had difficulty putting weight on his left foot as he attempted to get up. He hobbled to the Sabres bench, then fell to his knees while attempting to get through the door.
Game 3 of the series is Monday.
The Associated Press contributed to this story.