Ott in OT.
The Canadiens were frustrated again in trying to win a sixth straight game.
A heroic third-period comeback featured goals by Max Pacioretty and Colby Armstrong.
But it went for naught when P.K. Subban went for a big hit on the boards and took an ill-advised high-sticking penalty in overtime.
Consensus was the refs blew the call, but what does it matter?
With one second remaining in the Subban penalty, Steve Ott buried the rebound of a Jordan Leopold shot.
Jhonas Enroth was spectacular in nets for Buffalo as the Canadiens outshot the Sabres 26-8 through the last 40 minutes of regulation time. He made 32 saves on the night.
Carey Price was beaten three times on 21 shots.
Buffalo, with the power play, scored on their third shot of OT.
The Canadiens retain their hold on first place in the Northeast Division as Boston lost 3-1 in Winnipeg.
The Bruins still hold a game in hand but are two points behind the Canadiens.