DENVER -- St. Louis defenseman Colton Parayko would much rather block shots than throw punches.
Challenged by Colorado captain Gabriel Landeskog to drop the gloves late in the third period, well, he really had no choice. Parayko put up a good fight, too.
Same goes for the Blues, who are making things interesting down the stretch in the Central Division.
David Backes started the scoring in a three-goal first period, Anders Nilssonmade 19 saves in relief of an injured Jake Allen, and the Blues beat the Avalanche 5-1 on Sunday night.
With that, St. Louis pulled within two points of Dallas in a tightly packed division race. Chicago remains four points behind the Blues.
"We know what's in front of us. We know what's behind us," defenseman Alex Pietrangelo said. "But the biggest thing for us is worrying about ourselves. If we play like we can, we're going to put ourselves in a good position. We want to make sure we're going full speed going to the playoffs."
The Avalanche moved to the brink of postseason elimination. Still, they maintained their slim playoff hopes with Minnesota's loss to Winnipeg. They trail the Wild by five points for the final Western Conference berth and just three games left (two for the Wild).
"We need to learn how to win," Avalanche coach Patrick Roy said. "We need to change the mindset. I think we have a losing mindset right now. I think we have to find ways to believe more in ourselves."
Magnus Paajarvi, Parayko and Pietrangelo also scored for the Blues. Troy Brouwer added an empty-netter with 2:55 remaining.
Both teams switched their starting goalie for the second period. The Avalanche inserted Calvin Pickard after Semyon Varlamov gave up three goals on 14 shots.
More of a surprise, though, was when Nilsson replaced Allen. After the game, Blues coach Ken Hitchcock confirmed it was due to an injury. He's not sure the nature of Allen's injury or when exactly it happened.
"We'll know a little more on Jake tomorrow," Hitchcock said. "Hopefully, it's day to day."
Allen was playing well, stopping 11 shots, before giving way to Nilsson, who lost the shutout with 4:14 remaining as Matt Duchene tipped in a shot by Mikkel Boedker.
It was Duchene's 30th goal of the season and he celebrated -- his teammates even grabbed the puck for him -- but it drew the ire of Roy.
"The thing I have a hard time is the reaction of Dutchy after he scores. It's a 4-0 goal ... big cheer. Are you kidding me? What is that?" Roy said. "I mean, it's not the (reaction) we want from our guys, not at all."
It hasn't been much of a home-ice advantage for Colorado this season, with the team going 17-19-4 at Pepsi Center. The Avs have dropped four straight at home and been outscored 17-5.
"We're fighting for our lives," Duchene said. "We're going to have to show what kind of mental fortitude we have, and right now it's not as good as it could be and we need to be better."
Pietrangelo all but sealed the win with a goal early in the second period that made it 4-0. St. Louis has scored at least four goals in 11 of its last 15 games.
The Blues opened a three-goal lead in the first period -- all after the Avalanche looked as though they were about to take a lead themselves.
Allen stopped John Mitchell's bid for a short-handed goal early in the first period. That led to a break the other way, with Backes sending a pass over toVladimir Tarasenko, who sent it right back to Backes as the forward easily beat Varlamov.
"Jake was awesome again in the first period," said Parayko, who along with Landeskog was sent to the penalty box for 5 minutes for fighting. "He played outstanding, just like the goaltenders have all season. Can't say enough good things about it."
Nilsson saw his first action since March 14. ... The Blues were without forwardRobby Fabbri (lower body) and defenseman Jay Bouwmeester (upper body), but defenseman Carl Gunnarsson (lower body) returned after not playing the last three games. ... Avalanche D Nikita Zadorov sat out with a concussion. ...Nathan MacKinnon (knee) and Eric Gelinas (elbow) both missed their seventh game in a row.