ST. LOUIS -- Fifteenth in the Western Conference standings, the St. Louis Blues are still trying to earn one of the eight playoff spots.
"It's going to be a dogfight every game," Blues defenseman Barret Jackman said. "We just want to give ourselves a chance. You never know what can happen."
David Perron also had a goal and added an assist, and T.J. Oshie and Keith Tkachuk added goals. The Blues have earned points in nine of their last 10 games, going 6-1-3. Mason improved to 5-1-1 in his last six starts.
Chris Stewart scored for Colorado, just a point ahead of the Blues in the standings.
The Blues, who entered the second period down by a goal, scored three times in the first 4:51 of the period.
"We had a really good first period," Avs coach Tony Granato said. "Then, we made a couple mistakes early in the second period and the puck went in the net and gave them all sorts of momentum."
Stewart opened the scoring 11:56 into the first, beating Mason with a backhander following a behind-the-back backhand pass from Wojtek Wolski. Colorado took advantage of
Tyson Strachan's giveaway near center ice on an outlet pass from his own zone.
"The first period was ours," Granato said. "The second period was more theirs and that's where the game was taken over and won."
The Blues scored three times in the second to grab a 3-1 lead.
"If we needed a script tonight as how not to play and how to play, it would be the difference between the first and second period," Blues coach Andy Murray said. "The first period, we tried to play like the Russian Red Army team, finesse our way through the neutral zone and in the second and third period, we played with the lineup we have and played the kind of game we're capable of playing."
Oshie redirected Jeff Woywitka's slap shot past Peter Budaj 56 seconds into the period to tie it. Tkachuk notched his 16th of the season at 4:20 off a feed from Boyes, who stole the puck from Colorado defenseman Jordan Leopold and fed Tkachuk in the left circle. Tkachuk ripped a slap shot over Budaj. Boyes scored at 4:51 with a backhander.
Perron took a feed from David Backes in the slot and snapped a shot over Budaj's left shoulder 49 seconds into the third to give St. Louis a 4-1 lead and a stranglehold on the game.
"Obviously, you'd rather have a three-goal lead than a two-goal lead," Backes said. "It's a sign that we weren't sitting back and letting them take the game to us."
G Manny Legace, placed on waivers Friday by the Blues, went unclaimed and has been assigned to Peoria of the AHL. He will report Monday. ... Avs F Milan Hejduk had a four-game goal-scoring streak snapped Saturday. He had five goals in that stretch. ... Tkachuk has 25 goals and 52 points in 51 career games against the Avs. ... Backes and Avs F Cody McLeod are the only players in the league that have 10 or more goals (Backes 17, McLeod 12), more than 100 penalty minutes (Backes 129, McLeod 112) and more than 100 hits (Backes 129, McLeod 130). ... Mason has stopped 138 of the last 142 shots he has faced over the last seven games. ... The Blues have killed off 35 of the last 36 penalties against them.