Steve Ott netted a pair of goals, including the game-winner 2:16 into overtime, as the Buffalo Sabres came through with a 3-2 triumph over Montreal to end the Canadiens' five-game win streak.
Tyler Ennis also scored and Jhonas Enroth turned in a solid 32-save performance to help the cellar-dwelling Sabres top their Northeast Division rivals and prevail for only the second time in their last eight outings.
"It was a huge game for us, we needed this," said Ott. "We finally found a way to close out games, and that's probably one of the reasons why we've struggled all season."
Ville Leino contributed a pair of assists to the victory.
Though Montreal failed in its attempt to win six in a row for the first time since March 6-16, 2010, it still managed a point after Max Pacioretty and Colby Armstrong each had third-period tallies to rally the Habs back from a 2-0 deficit.
"We battled back, and it's actually good character to battle back and send it into overtime," said Armstrong.
Carey Price finished with 18 saves for the Canadiens.
Buffalo rode a pair of early goals and some excellent work from Enroth between the pipes to a 2-0 lead into the third period, but Montreal kept the pressure on in the final frame and finally broke through.
The rally began when Pacioretty received an on-target behind-the-net feed from Brendan Gallagher and fired a wrister past Enroth just over seven minutes into the session.
It remained a 2-1 game until late in the third, when Montreal's Alex Galchenyuk put a well-placed centering pass to a wide-open Armstrong in front and the veteran forward put home a backhander with just 3:51 remaining in regulation.
Buffalo was able to take back the momentum during the early stages of OT, however, thanks to Enroth's critical save on a Brian Gionta re-direct attempt near the end of regulation and a high-sticking call on Habs defenseman PK Subban with 17 seconds elapsed in additional time.
Montreal appeared on its way to killing off the penalty, with Price coming up with a kick save on Jordan Leopold's blast from the left circle. However, Ott skated in uncontested up the right side to knock in the rebound with only one second to go in Subban's infraction.
Ott gave Buffalo a 1-0 edge with an unassisted tally 7:47 into the contest, forcing a Canadiens' turnover and beating Price to the glove side immediately after the takeaway.
Ennis made it a two-goal lead by tipping home Tyler Myers' long drive 1:01 prior to the first intermission, and Enroth kept Montreal off the board all throughout the second period despite the Canadiens recording an 11-2 shot advantage.
"I felt good out there and the team played very well," Enroth remarked. "I stayed with it after losing a 2-0 lead, looking for the next shot. Tried to stay focused and stay sharp."
Sabres forward Patrick Kaleta saw his first game action since serving a five- game suspension for an illegal hit on the New York Rangers' Brad Richards on Mar. 3. He was eligible to play in Sunday's game at Washington, but was a healthy scratch ... Buffalo improved to 10-1-1 in the last 12 matchups between the teams and has posted a 6-1-0 mark at the Bell Centre over that span ... Canadiens forward Michael Ryder returned after sitting out Saturday's win at New Jersey with a lower-body injury ... Montreal center Tomas Plekanec had a four-game goal streak halted.