What did we learn?
Daniel Brière has to play and will ... at least for a while.
Brière scored twice and assisted on Brian Gionta's goal, which brought the Canadiens back from a 3-1 deficit before Clarke MacArthur scored a power-play goal 58 seconds into overtime to win it.
Colin Greening scored 13 seconds into the game.
And After Brière tied it 1-1, Ottawa got two in 14 seconds from Mark Stone and Erik Condra to take control.
The Senators had a 34-29 shot advantage.
MacArthur wins it
With the Senators on a power play, patient passing set up Clarke MacArthur for his 14th of the season.
A line is born
Daniel Brière, with his second of the game, and Brian Gionta brought the Canadiens back from 3-1.
And Carey Price kept it at 3-3.
On to OT, with P.K. in the box.
Each team had seven shots, the best of which was a Lars Eller backhander Craig Anderson got a pad on.
Michel Therrien juggled his lines: Daniel Brière joined Tomas Plekanec and Brian Gionta, moving Rene Bourque to the Eller-Galchenyuk line and dropping Brandon Prust down with Travis Moen and Michaël Bournival.
Josh Gorges was paired with P.K. Subban and Francis Bouillon dropped down to the third pairing with Douglas Murray.
The Canadiens are 1-12-1 when trailing after 40 minutes,
Daniel Brière, fresh from a two-game penance in the pressbox, converted a Travis Moen pass to erase the lead Colin Greening gave Ottawa 13 seconds into the game.
The jubilation didn't last long.
A giveaway at the Canadiens blueline sent Mark Stone in alone for his first of the year.
A mere 14 seconds later,Erik Condra banked one off Francis Bouillon's skate and past Carey Price.
The Canadiens failed to convert both a four-minute advantage and a 5-on-3 that lasted 45 seconds.
Shots were 14-10 for the visitors.
Carey Price wasn't stellar on the Stone goal but made a brilliant late-period save on Bobby Ryan.
Oh, and there's a bat flying around the Bell Centre.
The Canadiens, who haven't played in Montreal since Dec. 17, make their 2014 Bell Centre debut Saturday night against an Atlantic Division rival.
Ottawa, sitting ninth in the Eastern Conference, is nine points behind the Canadiens and has played one more game.
The Senators have scored 13 more goals than the Canadiens – 122-109 – but have allowed an eye-popping 40 more goals-against: 138-98.
You wouldn't have attributed defensive shortcomings to the Senators when the teams met in Ottawa on Nov. 7. Robin Lehner made 33 saves in a 4-1 win, the only Canadiens goal coming from Andrei Markov during a first-period power play.
Ottawa rides a three-game winning streak into the Bell Centre, where the Canadiens are 12-7-2 this season.
Subtext to the game: Max Pacioretty, who has 19 goals this season, will be on the U.S. Olympic team next month. Bobby Ryan, who's scored 18, won't be in Sochi.
Chris Neil and Jason Spezza are out for Ottawa.
Daniel Brière and Alexei Emelin draw back in for the Canadiens. Ryan White is injured and Raphael Diaz is a healthy scratch.