The Canadiens have been seeking retribution against the Senators since last spring when Ottawa eliminated them in the opening round of the playoffs.
Montreal finally got what it wanted on Friday night as they defeated the Senators 7-4, making Ottawa's chance at returning to the post-season that much more difficult as the club sits seven points out of the final wild-card berth with just five games remaining.
Max Pacioretty had a hat trick for the Canadiens.
"This year we definitely felt like we owed them a little payback for last year in the playoffs and our games have been heated against them," said Pacioretty. "It's not just on the scoreboard that feels good it's seeing guys step up and stand up for their teammates. I think that's one of the more rewarding feelings about the night."
Andrei Markov, Mike Weaver, Lars Eller and David Desharnais also scored for Montreal (44-27-7) as Peter Budaj stopped 39 shots for his 10th win of the season.
Zack Smith scored twice for the Senators (32-31-14) while Ales Hemsky and Mika Zibanejad had the others. Craig Anderson faced 22 shots.
Ottawa jumped out to a 3-0 lead before the game was six minutes old, but then allowed the Canadiens to score seven straight times.
"It's hard to pinpoint exactly what happened," said Smith. "We lost control of the game. We were up three goals and it didn't take them long to get those back and after that it was hard to get any traction. A couple of soft plays and turnovers and they're in our net."
Smith had few answers as to why or how the Senators could crash so badly, but admitted it wasn't pretty.
"We say playing Montreal it's an easy game to get up for," said Smith. "That's embarrassing. We're up 3-0 and they score seven straight."
Senators coach Paul MacLean was at a loss for words after the game.
"I'm numb," he said. "We came out and played and got the lead 3-0 and then we stopped playing. We stopped doing the things that made us successful."
With already two on the night, Pacioretty completed his hat trick at 1:09 of the third and Desharnais made it 7-3 midway through the third beating Anderson up high.
The Senators finally managed to put an end to the onslaught 14 minutes into the third as Zibanejad beat Budaj.
Despite being outshot 15-4 in the second the Canadiens scored twice to take a 5-3 lead after 40 minutes.
"Obviously you look at the shots and we got some favourable bounces and that's just the way it goes some nights," said Pacioretty. "It just shows our last two games against them you're never down and out."
Montreal took its first lead of the game as Eller jumped on a rebound early in the second to make it 4-3.
Ottawa appeared to tie it up on the ensuing play, but the goal was called back due to incidental contact on the goaltender.
The call left the Senators extremely frustrated as they felt video review clearly showed there was no contact by an Ottawa player on the play.
"It was a bad call, sorry, we disagreed with the call," said Smith. "He was adamant right from the start that there was contact and there wasn't even discussion. Usually when that happens there's discussion, but I have to watch what I say."
Montreal made it 5-3 on Pacioretty's second of the night as he took advantage of a Senators turnover and broke in alone to beat Anderson through the legs.
The game was made that much more interesting after Erik Karlsson checked Brendan Gallagher hard into the boards and Alex Galchenyuk took offense, leading to Karlsson and Galchenyuk exchanging a couple punches.
"All season, every time we've played them it's been bizarre games," said Montreal coach Michel Therrien. "I liked the way our team stood up for one another. We were down 3-0 and came back and we saw a lot of good things. We showed a lot of character."
Trailing 3-0 the Canadiens got on the board as Markov scored off a bad angle down low on Montreal's second shot of the game. Two minutes later Weaver's point shot made it past a screened Anderson.
The comeback was completed as Pacioretty got past Ottawa's Eric Gryba on a bouncing puck and beat Anderson between the legs.
"It's brutal," said MacLean. "We're at home and we stopped playing. It's not right."
After giving up the early lead, Montreal's P.K. Subban saw just 37 seconds of ice time in the first and didn't get another shift until the Canadiens went on the power play at the two-minute mark of the second.
Ottawa opened the scoring at the two-minute mark of the first as Smith scored his first off his backhand.
The Senators made it 2-0 just over two minutes later as Hemsky tipped Patrick Wiercioch's point shot and it was 3-0 as Smith scored his second of the game off a great pass from Zibanejad.
The Senators played the third without Hemsky, who left with an upper body injury.
Ottawa next faces the Rangers Saturday night in New York, while the Canadiens return home to host the Detroit Red Wings.
Notes: C Jason Spezza returned to the Senators lineup after missing the last two games. The Senators were without D Jared Cowen (lower body, day-to-day), LW Colin Greening (lower body, day-to-day) and RW Bobby Ryan (sports hernia, out for season). LW Matt Kassian was a healthy scratch. The Senators used the last of its call-ups as it did the paperwork to change Jean-Gabriel Pageau's call-up from emergency to regular recall… Montreal D Douglas Murray served the first of his three-game suspension. RW Rene Bourque and D Nathan Beaulieu were a healthy scratch. RW Dale Weise missed the game with an upper body injury.