Miikka Kiprusoff made his 16th straight start Sunday night. He doesn't seem to need a break.
Calgary broke a scoreless tie at 5:39 of the third period after a bad sequence from Blues defensemen Carlo Colaiacovo and Tyson Strachan.
Strachan failed to control Colaiacovo's cross-ice pass deep in his own end. When Strachan did corral the puck, his clearing attempt was knocked down by Alex Tanguay, who fed Moss. He quickly snapped his 15th goal past Ben Bishop before being wiped out by a sliding Colaiacovo.
"Tangs made a great play to get it over to me and I knew I had to get it away quickly," Moss said.
St. Louis pressed hard in the closing moments and nearly tied it with 3 minutes remaining.
Brad Boyes -- who was traded to Buffalo for a second-round pick after the game -- banked a shot in off Kiprusoff from the side of the Flames' net, but the goal was waved off by back referee Dan O'Rourke who judged St. Louis forward David Backes had knocked the puck out of the air with a high stick.
One minute later, Patrik Berglund's shot beat Kiprusoff cleanly but hit the post.
Calgary (32-23-9) finished its five-game homestand 3-1-1 and moved into sole possession of sixth place in the Western Conference.
"This time of year, you need to be prepared to win games whatever way," Flames coach Brent Sutter said. "Games are going to be tight and you've got to win those tight games. It's playoff hockey, you're not going to get 6-5, 7-6 hockey games. You look around the League at all the games that matter in the standings and they're all one-goal and two-goal games and low scoring."
St. Louis (28-25-9) lost for the fourth time in its past five games and remains in 13th place in the conference.
The two teams meet again Tuesday night at the Scottrade Center in St. Louis.
"These points are so big, especially for those guys who are barely in and have played a few more games than the other teams and for us who are clawing for our lives," Backes said. "We knew it was going to be like that, a playoff atmosphere, and you see a 1-0 game where it's try to make the other team make the mistake that costs them the goal and they were able to do that to us."
Bishop, a 6-foot-7 rookie making just his third start, had a 39-save shutout Friday in the Blues' 5-0 win over Edmonton.
He wasn't as busy Sunday, but still had to come up big on a couple of occasions.
Right after the Flames took the lead, Bishop denied Jarome Iginla on a heavy slap shot from the wing.
At the other end, Kiprusoff was sharp.
His best stop came midway through the second period when a lane opened up for Alex Pietrangelo. The Blues' defenseman skated in all alone, but Kiprusoff kicked out a pad as Pietrangelo went to his backhand.
"He certainly stole one for us tonight," Moss said. "They were shooting everything and they were coming pretty hard and he shut the door and made some huge saves when we needed them."
Kiprusoff was busiest in the third period when he faced 14 shots. It was his 39th career shutout.
"If we played the way we did tonight for our first 61 games, I'd like our chances and our record better than it is right now," Backes said. "But, there are no moral victories this time of year, we need to climb the standings and make sure we're getting our two points and the bottom line is we didn't get it done tonight."
Ducks 3, Avalanche 2 | HIGHLIGHTS
Todd Marchant snapped a 70-game goal drought, Brandon McMillan got the go-ahead score during a 4-minute power play with 8:37 remaining, and Anaheim ended a five-game losing streak with a victory against Colorado at the Honda Center.
"I don't know what my longest drought was prior to this. It certainly wasn't anywhere near this, but I didn't let it get me down mentally," Marchant said. "I knew that I have many other roles here. I mean, if this team was counting on me scoring goals, we wouldn't be going very far.
"The bottom line is about wins this time of year, getting into the playoffs and seeing how far it takes you -- not how many goals I get. This is the best time of the year -- to be playing for something. It was a big two points for our hockey club, and now hopefully this can jump-start us."
Ryan Getzlaf also scored and Dan Ellis made 22 saves in his second start for the Ducks since being acquired last Thursday in a trade that sent ineffective backup goalie Curtis McElhinney to Tampa Bay.
McElhinney had allowed 19 goals in four starts while filling in for first-time All-Star Jonas Hiller, who has been sidelined for six games because of lightheadedness after his 12-save shutout win over Edmonton.
Kevin Porter and David Jones scored for the Avalanche, who have lost 13 of 14 and sit next-to-last in the Western Conference. They have lost seven straight at Anaheim.
"I thought it was our best game in a long time," Avs coach Joe Sacco said. "We played as a team tonight. We were alive and there was desperation in our game. Guys were playing for each other. At the end, the double-minor was the turning point in the game."
Marchant's goal, which came on his 48th shot of the season, was his first since March 17, 2010, against Chicago. It gave Anaheim a 2-1 lead at 17:51 of the second period.
The 17-year veteran center carried the puck into the Colorado zone and fed it to defenseman Luca Sbisa, who threw it back toward the slot from the right circle and celebrated with the rest of the Ducks after Marchant stuck out his stick and redirected his 186th career goal past Peter Budaj.
"My son scored a goal the other day in his game and he said: 'Now it's your turn, Dad.' So everybody's been very supportive," Marchant said through a gap-toothed grin. "A lot of guys were poking fun at me. Even the linesmen were having fun with me. A lot of guys were saying: `Should we go get you the puck?' But it's all in good fun. I'll take the ribbing to get that first one out of the way. Every guy in this locker room was pretty happy for me."
Jones tied it less than 2 minutes into the third, beating Ellis high to the glove side through a screen with a wrist shot from the top of the left circle.
But Colorado wing Brandon Yip cut Francois Beauchemin with an inadvertent high stick at 8:19 of the final period, and the Ducks cashed in as McMillan converted a rebound of Bobby Ryan's one-timer from the left circle with 56 seconds left on the power play.
In a game that featured three fights before the 9-minute mark, Colorado opened the scoring at 12:07 of the first when Jonas Holos dumped the puck into the left corner and Matt Duchene made a touch pass into the crease that Porter deftly redirected past Ellis' stick while skating past him.
Anaheim's Lubomir Visnovsky, who came in tied for third in points among defensemen, limped to the dressing room less than a minute before the first intermission with a twisted knee after slamming on the breaks to avoid a check by Ryan Stoa in the neutral zone. But he was back for the start of the second period and started the play that led to the tying goal.
Colorado defenseman Erik Johnson retrieved the puck behind his net, but the forechecking Ryan made him cough it up to Corey Perry, who fed Getzlaf in the slot for a short wrist shot that beat Budaj to the stick side at 1:42.
Colorado is 1-4 since the trade that brought Johnson -- the first overall pick in the 2006 draft -- and center Jay McClement from St. Louis. McClement has yet to record a point for his new team, extending his overall drought to 10 games. He has just one goal in his last 31 games -- against the Avalanche, when his carom shot off the crossbar was upheld by video replay.
"We didn't have a very good start to the hockey game, but we built on our forechecking and got our game turned around in the second period," Ducks coach Randy Carlyle said. "You have to credit our players. They stuck with the program."
Bruins 3, Oilers 2 | HIGHLIGHTS
Michael Ryder had a goal and an assist as Boston made it five in a row on the road with a win at Edmonton.
For NHL.com's full recap, click here.