Paul Byron and Alexander Radulov beat Craig Anderson in a Shootout to secure the vital win.
The Canadiens managed to kill a penalty at the end of OT
Two quick goals by Phillip Danault and Brendan Gallagher gave the Canadiens a 3-2 lead seven minutes into the third period.
But Erik Karlsson – who else? – tied it up with a long-range shot at 15:03
Andrew Shaw got the game’s first goal, 2:37 into the second period.
The lead lasted 10 minutes before Derrick Brassard scored on an Ottawa power play, converting a perfect feed by Kyle Turris.
And 1:26 later, Ryan Dzingel tapped one in from close range to give Ottawa the lead.
Shots were 32-31 Canadiens through 65 minutes.
• On March 18, 1945, Maurice Richard became the first NHL player to score 50 goals. Dave Stubbs looks back at the milestone.