Blues 7, Avalanche 3: Alexander Steen scored twice to increase his league-leading total to 16 goals as St. Louis used a big second period to upend visiting Colorado.

Captain David Backes and Derek Roy had a goal and two assists apiece for the Blues, who equaled their largest single-game output of the season. Defenseman Jay Bouwmeester, Chris Stewart and Vladimir Tarasenko also tallied, T.J. Oshie had a career-high four assists and Jaroslav Halak made 21 saves to preserve the win.

Top overall pick Nathan McKinnon, Matt Duchene and Ryan O'Reilly countered for the Avalanche, who have dropped three of five following a 12-1-0 start. Jean-Sebastien Giguere and Semyon Varlamov combined to stop just 22 shots in defeat.

After Roy and McKinnon exchanged first-period goals, the Blues broke it open with a four-goal second. Backes started the onslaught with a power-play goal at 2:49, and Steen extended the advantage with a short-side snap shot at 7:16 that ended Giguere's night.

Tarasenko made it a 4-1 game just under five minutes later, pouncing on a loose puck to the left of Varlamov and slapping it just inside the left post. Stewart added a power-play goal at 14:39 to cap the explosion, and Steen's tally 2:11 into the third capped his third multi-goal game of the campaign.

GAME NOTEBOOK: Steen has scored in all but four games this season. ... St. Louis went 3-for-4 on the power play. ... Colorado came in having allowed just five goals in its previous three games combined.