Erik Karlsson scored the go-ahead goal late in regulation as the Senators grabbed Game 1 from the New York Rangers 2-1.
The Senators captain beat fellow Swede Henrik Lundqvist on shot that deflected off Rangers centre Derek Stepan
Lundqvist had been superb to that point for New York and finished with 41 saves.
Craig Anderson stopped 33 shots, beaten only by Ryan McDonagh.