The incident occurred in the second period near the Canadiens' net. As rookie Senators forward Mark Stone skated by Canadiens goaltender Carey Price, Subban slashed Stone, who pulled up injured on the play.
Subban was given a five-minute major and a game misconduct, ending his Game 1 prematurely.
Stone exited the game temporarily and returned to the locker room, but he returned to the Senators' bench around 10 minutes after the slash. Ottawa scored twice on the five-minute power play, but the team also gave up a shorthanded goal.
The Canadiens beat the Senators 4-3 to take a 1-0 lead in the series.
- Stanley Kay