Blues 5, Canadiens 1: Alexander Steen scored twice and Jaroslav Halak stopped 25 shots as host St. Louis cruised past Montreal.

After signing a three-year contract extension earlier Thursday, Steen quickly showed why he was worthy of the deal - equaling his single-season career high of 24 goals with a pair of first-period tallies. Chris Stewart, Jaden Schwartz and Maxim Lapierre also had goals as St. Louis climbed to 5-3-1 in December.

Brendan Gallagher scored the lone goal for the Canadiens, who have dropped four of six. Carey Price made 24 saves in defeat.

Steen kicked off the night in style, finishing off a short-handed 2-on-1 rush by firing T.J. Oshie's feed past Price at 4:20. Steen padded the lead at 7:55 with a quick wrist shot from the left faceoff circle that beat Price over his glove-hand shoulder, and Stewart made it 3-0 at 13:33 with a shot off Brenden Morrow's centering pass that caromed in off the post.

Gallagher put Montreal on the board with 7:09 remaining in the second period, batting home a rebound after his initial deflection from the edge of the crease hit Halak in the shoulder. Schwartz restored the three-goal edge at 12:21 of the third, keeping on a 2-on-1 break and whistling a wrist shot past Price following a Montreal turnover in the neutral zone.

GAME NOTEBOOK: St. Louis improved to 12-2-1 against Eastern Conference representatives this season. ... Halak has won each of his four career starts against his former team, stopping 96-of-100 shots. ... Canadiens D P.K. Subban has just three points - all assists - in his last nine games.