DENVER -- For the second time in two games, Ryan O'Reilly was the difference for Colorado.
That hasn't been a surprise to the Avalanche, who have watched him blossom in his third year in the NHL.
"He's been doing this for a while now. He's been playing very well," Colorado coach Joe Sacco said. "The kid's been showing signs of emerging as one of the top players."
The team's leading scorer, O'Reilly got the tying goal and then converted in the shootout to lift Colorado to a 3-2 victory over the St. Louis Blues on Friday night.
O'Reilly also had a goal and two assists Wednesday against New Jersey.
"Right from the drop of the puck tonight, I saw him along with his line really do a nice job for us," Sacco said.
O'Reilly, who also had an assist, lifted a backhander over the shoulder of Jaroslav Halak for the only goal in the tiebreaker. Milan Hejduk, who netted his ninth goal of the season in regulation, and Matt Duchene had already been stopped by Halak.
"He stood on his head like every game," O'Reilly said of Varlamov, who is 3-2 in his last five starts. "He is a huge reason why we win."
Kevin Shattenkirk and Patrik Berglund had goals, and Halak made 35 saves for the Blues, who had a four-game winning streak snapped. St. Louis is 7-1-3 under coach Ken Hitchcock since he replaced Davis Payne on Nov. 6.
"A shootout is a shootout," Hitchcock said. "We didn't extend the lead and it came back to haunt us."
With Colorado trailing 2-1, O'Reilly tied it at 9:34 of the third period with a wrist shot that beat Halak through a screen.
"It feels good to get the win, but I thought we'd have it in OT," O'Reilly said. "Unfortunately, it took a shootout to do it. We played well, we found a way to win."
The Avalanche nearly won it with 10 seconds left in overtime, but Halak reached back at the last moment to keep Ryan O'Byrne's shot from crossing the goal line.
"I was 100 percent sure that it didn't go in," Halak said. "They were celebrating, but they were celebrating too soon."
The Blues struck first, taking advantage of a hooking penalty on Paul Stastny when Shattenkirk scored his third of the season 8:55 in. Jason Arnott found Shattenkirk alone above the right circle, and he flipped a wrister through a screen that Varlamov never saw.
Colorado tied it at 13:55 when Hejduk sent a shot past Halak. O'Reilly set up the play from behind the net.
Stefan Elliott of the Avalanche hit the right post, but on the change of possession Berglund scored with a backhander off a pass from Stewart at 5:39. Stewart drew the defense to him, leaving Berglund more space in the slot to maneuver and get off a shot.
Colorado won back-to-back home games for the first time this season.
G Brian Elliott (10-1-0) is expected to start Saturday when the Blues host Chicago. ... The Blues are 0-3 in shootouts. ... Shattenkirk's goal ended Colorado's string of 14 straight penalties killed over four games. ... Colorado was 0 for 4 on the power play. ... The Avalanche have won five straight home games against the Blues.