"We're going to miss Hornqvist's energy. This game is rooted in emotion and passion. Hornqvist epitomizes that. We need to bring that up in order to be successful," Sullivan said, according to the team's official Twitter account.
He missed the Penguins' 3-1 loss to the New Jersey Devils on Saturday night.
Hornqvist is fourth on the Penguins with 31 points (16 goals, 15 assists) this season.