With the game tied 1-1, Winnipeg's Tobias Enstrom was whistled for interference with 2:13 left in regulation, giving St. Louis a man-advantage.
On the ensuing power play, the Blues passed the puck around the perimeter until Jay Bouwmeester directed it to the high slot, where Steen corralled the disc and shoveled a backhand shot past Ondrej Pavelec for the key goal.
Pavelec finished with 30 saves.
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