Allen, who has started four of five for St. Louis due to the struggles of veterans Brian Elliott and Jaroslav Halak, stopped all 28 shots to win his fourth straight. He is 7-1 since being recalled from the minors last month.
St. Louis have back-to-back wins in regulation for the first time since Jan. 24-25. The Blues have won four of five overall.
Alexander Steen celebrated his return to the lineup for St. Louis with a goal and two assists. Steen, who had missed eight games with a shoulder injury, scored his first goal since Feb. 15.
I downplayed the first one because I thought it's just a hockey game. We just want to win the game; it's against our rival and we want the two points. I downplayed it, but now having gone through the first one I look back and say, 'Geez, that was really cool.' I think as I've grown a bit older I've got a lot more appreciation for what we're allowed to do every day.
— Capitals forward Brooks Laich on the 2015 NHL Bridgestone Winter Classic, the second one of his career after 2011 in Pittsburgh