ST. LOUIS -- Center David Backes thought it was only a matter of time before the St. Louis Blues' struggling power-play started clicking.
He didn't know if it would happen Thursday night against the Colorado Avalanche, who came into the game against the Blues having killed off all 20 opponents' power plays in their first seven road games this season.
The Blues (12-2-3) set a franchise record by winning for the 12th time in their first 17 games.
It took less than two minutes into the game for that streak to end, as center Derek Roy scored the first of three power-play goals by the Blues en route to a 7-3 victory.
St. Louis converted just one of 14 power-play chances in its previous five games.
Left winger Alexander Steen scored twice for the Blues, although neither came on the power play, as he increased his league-leading total to 16. He extended his personal scoring streak to 12 games. Steen has 12 goals and four assists in that span.
Roy's goal just 1:54 into the game, five seconds after a minor penalty against the Avalanche, was followed by power-play goals by Backes and right winger Chris Stewart in the second period.
The loss marked the first time this season the Avalanche (14-4-0) lost consecutive games. It was also the first defeat this season for goalie Jean-Sebastien Giguere, who won his first five games while allowing just five goals on 165 shots.
The Blues temporarily chased Giguere in the second period as they converted three of their first 14 shots, including the power-play goal by Backes just eight seconds into a Colorado penalty, part of a four-goal explosion in a span of 11:50 in the period. Giguere returned to the net for the final period.
Stewart added the third power-play goal for the Blues, the first time they scored more than two power-play goals in a game this season. They scored one or no power play goals in each of their previous seven games.
Right winger Vladimir Tarasenko and defenseman Jay Bouwmeester scored the other Blues goals, and right winger T.J. Oshie earned four assists, the first four-point game of his career. Roy added two assists as the Blues matched their highest scoring game of the year.
Colorado's goals came from 18-year-old rookie center Nathan MacKinnon, on a power play 5:30 into the first period; from center Matt Duchene, his 12th of the season; and from center Ryan O'Reilly, after the Blues opened up a 6-1 lead in the third period.
Blues goalie Jaroslav Halak made 21 saves. Giguere finished with 18 shots, and Colorado goalie Semyon Varlamov stopped four of the six shots he faced.
NOTES: The Blues and Avalanche, who became division rivals in the NHL's realignment, met for the first of four meetings this season. ... The Blues officially signed free agent D Carlo Colaiacovo to a one-year contract. He helps provide depth after D Jordan Leopold was lost for two months because of a hand injury. Colaiacovo, who did not dress for the game, played with the Blues from 2008 through 2012. He will wear uniform No. 13, the first Blue to wear that number since Dan Hinote in 2008-09. ... For the game, the Avalanche moved 18-year-old rookie Nathan MacKinnon from center to right wing. He played on a line with C Paul Stastny and LW Gabriel Landeskog. ... The Blues will conclude a five-game homestand with a game against the Carolina Hurricanes on Saturday night. The Avalanche return home Saturday night to host the Florida Panthers.