Patrik Berglund’s empty-netter completed a hat trick for the St. Louis forward.
Berglund’s second of the game gave St. Louis a 3-2 lead with less than a minute left in the second period.
Al Montoya looked weak on on that one and on David Perron’s goal, giving St. Louis a 2-1 lead, 7:20 into the period.
Thirteen minutes into the middle period, Alex Radulov keyed a dominant shift that culminated in Max Pacioretty’s 28th of the season, tying the game at 2-2.
Berglund got St. Louis on the board fewer than four minutes into the game.
Mike McCarron was beaten on the boards behind the Canadiens’ net, and the puck was fed out to Pietrangelo whose shot was tipped past Al Montoya by Berglund.
The Canadiens went 15 minutes without a shot on Jake Allen.
But at 16:39, Shea Weber blasted one past Allen for his 13th of the season. Alex Radulov had done the spade work, feeding the puck out from behind the St. Louis net.
Shots were 30-22 for the team that lost.