Washington took a 3-0 lead midway through the second when Vrana stole the puck from Mark Stone and beat McKenna with a flashy move. Kempny made it 4-0 at the 13-minute mark when his point shot deflected off Cody Ceci.
The Senators trailed 2-0 after the first period, but it could have been more if it wasn’t for McKenna.
Connolly opened the scoring at 1:32 when he redirected Jonas Siegenthaler’s point shot.
“When we’re ahead in games we’re definitely better,” Connolly said. “We know when we’re behind we have a lot of guys that can hurt you as well, but when we get the first one we settle in and definitely on a back-to-back it makes it easier so it was good to get that first one.”
McKenna made impressive glove saves on Andre Burakovsky and Travis Boyd. Bobby Ryan also stopped a sure goal when McKenna was caught out of position.
The Capitals took a two-goal lead late in the period when Niskanen got behind Ceci and tipped Nicklas Backstrom’s pass for his fifth of the season.
NOTES: With Anderson dealing with an upper-body injury, Marcus Hogberg was recalled from the American Hockey League’s Belleville Senators. … The Senators honored LPGA golfer and Smiths Falls, Ontario, native Brooke Henderson prior to the game and had her drop the puck. … Ottawa’s Tom Pyatt and Max Lajoie were healthy scratches. … Washington’s Tyler Lewington made his NHL debut Saturday night.
Capitals: Host Carolina on Thursday night.
Senators: Play at the New York Islanders on Friday night.
More AP NHL: https://apnews.com/NHL and https://twitter.com/AP_Sports