Sabres coach Ron Rolston confirmed Leino's injury following Thursday's practice.
"It happened in the first period, probably about three-to-four shifts in," Rolston said. "It was just sore and it seized up overnight, and we had it checked."
Leino, who played 12:36 in the game with no shots on goal, was limited to eight games last season due to hip and lung injuries.
"He's going to get a good opportunity," Rolston said. "I like everything about him. His attitude, the way he works, preparation. He's a good detail player. This will give him a good opportunity to play with some good players and show us what he can do. It's a good thing. He's ready."