Game 2 of the best-of-seven series is Saturday in Washington.
It's the third consecutive season these two teams are facing each other in the playoffs and the fourth time in five years. The Rangers eliminated the Capitals in seven games in the second round last season.
But Washington is playing a livelier brand of hockey under first-time NHL head coach Adam Oates, a Hockey Hall of Fame forward who shifted Ovechkin from left wing to right wing and helped design the Capitals' league-best power play.
The Rangers drew the fewest penalties of any team this season, but they already accumulated four by early in the second period, and Ovechkin capitalized on No. 4.
Senators 4, Canadiens 2 • Craig Anderson made 48 saves in a spectacular goaltending performance as Ottawa host Montreal in Game 1 of their playoff series.
Jakob Silfverberg and Marc Methot scored early in the third period and gave Ottawa a lead in the best-of-seven series, with Game 2 set for Friday night at the Bell Centre.
Erik Karlsson and Guillaume Latendresse also scored for the Senators, who were outshot 50-31 but saw Anderson easily win the goaltending duel with Carey Price, who was beaten twice through the pads.
The first playoff series between the Northeast Division rivals didn't take long to get nasty.
Montreal center Lars Eller was wheeled off on a stretcher bleeding heavily from the nose and was taken to a hospital with what the team said were head and facial injuries after he was caught with a shoulder to the face on an open-ice hit from Senators defenseman Eric Gryba.