Capitals improve to six in a row, Senators down Blackhawks in OT
T.J. Oshie scored the match-winning goal 8:17 into the third period after the Canadiens drew level six minutes earlier through Brian Flynn.
Tom Wilson opened the scoring for the Caps early in the opening period before Lars Eller equalised and Oshie netted his first of the game.
Washington leapfrogged the New York Rangers at the summit of the Metropolitan division on goal difference, as the Canadiens fell to their second defeat in three games.
Mike Hoffman scored 30 seconds into overtime to help the Ottawa Senators beat Stanley Cup champions Chicago Blackhawks 4-3.
Hoffman netted the game's opener after 92 seconds in a back-and-forth meeting, with the Blackhawks falling two goals behind inside the first period before twice drawing level.
A pair of second-period goals from Chris Wagner and Matt Duchene helped the Colorado Avalanche seal back-to-back wins via a 2-1 victory over the Rangers.
Mike Cammalleri scored twice as the New Jersey Devils crushed the Carolina Hurricanes 5-1 and the Minnesota Wild shutout the Toronto Maple Leafs 1-0.
The Detroit Red Wings eased past the Arizona Coyotes 5-1 thanks to goals through Justin Abdelkader, Niklas Kronwall and Gustav Nyquist in the first period.
Elsewhere, the Florida Panthers defeated the Nashville Predators 2-1.
Patrick Sharp and Jason Spezza scored late as the Dallas Stars saw off the Vancouver Canucks 4-2.