Ovechkin has scored 33 points (15 goals and 18 assists) in 21 games.
"He's rolling," Capitals coach Peter Laviolette said. "He's still shooting too. It's not like he couldn't have scored tonight. He's still unleashing. But I always think there's that area where you've got to make the right decision. It can't just be about one thing or the other thing, so he's done a really good job of that."
Ilya Samsonov, who had a shutout in his two previous starts, made 25 saves for the Capitals (12-4-5), who are 7-1-1 in their past nine games.
Jake Evans and Artturi Lehkonen each had a goal and an assist for the Canadiens (5-14-2), who are 1-4-1 in their past six games. Jake Allen made 28 saves in his return after missing four games because of a concussion sustained at the Detroit Red Wings on Nov. 13.
The Canadiens, who defeated the Nashville Predators 6-3 on Saturday, were trying to win consecutive games for the first time this season.
"It's clear we're not the same team the second game," Evans said. "We let off the gas a little bit. Now we're playing some good teams and they make you pay pretty quickly."
Injuries have required players from Hershey of the American Hockey League to step in for the Capitals, including forwards Beck Malenstyn and Michael Sgarbossa on Wednesday.
"These guys getting called up here, we're not hiding them," Laviolette said. "We've got to keep the train moving down the track and these guys have come up and done an excellent job."
Nic Dowd gave the Capitals a 1-0 lead at 3:34 of the first period. Dowd went around Jeff Petry, lost the puck as he attempted to shoot, but regained it and went around the back of the net and scored on a backhand.