Auston Matthews, Mitchell Marner and Connor Carrick scored in the third period, Jake Gardiner had three assists, and Frederik Andersen made 15 saves for the Maple Leafs (26-17-5), who were 0-1-3 in the past four games.
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"The message was 'enough is enough,'" Carrick said of Marleau's speech. "We really need to execute for each other and make sure we're making positive plays. I think there was a sense of urgency in the third, kind of a bite or a hunger. It's hard to identify, but you know what it is when you see it and I think we had it then."
"When guys like Patrick Marleau step up and say something in the locker room, guys are going to listen," Matthews said. "He's a pretty soft-spoken guy, but when he says something, you've got to listen up, and that kind of got the ball rolling."
Matthews scored his 20th goal of the season at 2:53 to make it 3-2, getting behind Senators defenseman Cody Ceci and backhanding the puck into the net.