Rookie defenseman Cale Makar added a power-play goal and an assist for the Avalanche, who also ended a six-game losing streak to the Blues, including two losses earlier this season in St. Louis. Mikko Rantanen J.T. Compher also had power-play goals, and Joonas Donskoi had the other goal for the Avalanche. Samuel Girard finished with four assists.
"Today was a good start in the right direction," said Avalanche goalie Philipp Grubauer, who had 24 saves. "Everybody was going. We need that. (The Blues) are a really good team, so huge points for us. We didn't do well the last couple games against them. It was a good statement game for us. We need to keep collecting points and playing the right way. You miss a point here and there, it's going to cost you in the end."
MacKinnon said he liked the way the Avalanche responded with a big third period after the Blues had fought back from a three-goal deficit to make a game of it.
"I think we were just due, honestly," MacKinnon said. "We were giving all the opponents their goals in the third, we had bad breakdowns. Something just felt kind of different tonight when they made it 3-2. There was no panic and Cale had a big goal, and that kind of iced it. We knew we needed some maturity from everybody at that time."
The Blues trailed 3-0 before Thomas got St. Louis on the board with a wraparound shot that beat goalie Philipp Grubauer with 6:18 left in the second. With the Blues on the man advantage, Ryan O'Reilly won a faceoff, sending the puck to Pietrangelo, who knocked in a shot that pulled St. Louis to within a goal with 3:41 left in the period.
Colorado answered with its second power-play goal of the night with 15 seconds remaining in the middle period on a shot by Makar, allowing the Avalanche to regain a two-goal lead.
Kadri, Compher and Donskoi scored 7:23 apart in the third to push Colorado's lead to 7-2 with 5:41 to go.
"This team, we usually play them well when we play them really tight," Pietrangelo said. "I think we gave them too many chances. A team this skilled, you give them chances, breakaways, 2-on-1s, 3-on-2s, they're going to find a way to score. We gave them too many."
Penalties also were an issue for the Blues, who gave up three scores when Colorado was on the power play.
"We took too many penalties," Blues coach Craig Berube said. "We can't put us down 5-on-3 against that team."
MacKinnon converted a St. Louis turnover in Colorado's zone into a breakaway that led to the game's opening goal with 11 seconds left in the first as he wristed a shot past Binnington.
The Avalanche added two goals in the first half of the second period. Kadri knocked in a rebound for his first of the night at 3:20. The Avalanche were in a 5-on-3 power play when Rantanen got a cross-ice pass from Makar and wristed a shot into the net from center of the right circle at 7:40.
The Avalanche have the most points (52) through the first 41 games of the season since hitting the halfway point of the 2013-14 season with 56 points. ... Avs F Donskoi matched his career-high in goals (14) while with San Jose in 2017-18 and 2018-19. ... Pietrangelo has nine points in his last six games (four goals, five assists).
Blues: Wrap up three-game road trip at Vegas on Saturday night.
Avalanche: At New Jersey on Saturday night to open a three-game trip to the New York area.
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