What happened: The Montreal Canadiens lead the Buffalo Sabres after the first period, with Cole Caufield trending as a key driver of the early push, per ESPN's live broadcast. The game is airing on ESPN and the ESPN App. Buffalo had a goal overturned earlier in the sequence following a Montreal coach's challenge.

Why it matters: Caufield's hot start matters because the same Cole Caufield who hit 40 goals this season has been Montreal's offensive engine all year. A first-period lead in this series shifts momentum after the Sabres struck first earlier in Game 3, putting Buffalo on the back foot in a tightly contested matchup.

What to watch: Watch whether Caufield converts his early pressure into goals and whether Buffalo can respond in the second period. Special teams and shot share after intermission will signal if Montreal can hold the lead.