The Flames had won four straight and had points in six games, suddenly surging and playing like the team most fans expected this season.
The way they expected this season.
The Avalanche, meanwhile, were considered by some pundits as the best team in the league right now heading into the tilt, winners of six straight.
They were second in the Western Conference at 19-8-2, and were 8-2 in their last 10 outings.
So, Monday was a litmus test.
Folks wanted to see just how far this Flames team had come.
They answered that emphatically.
They battled back from 1-0 and 2-1 deficits to win a thriller 5-4 in overtime.
Sean Monahan had the dagger in extra time, Derek Ryan, Matthew Tkachuk, Andrew Mangiapane and Michael Frolik also scoring, while David Rittich was a beast between the pipes - yet again - making 28 saves.
Just 35 seconds into the tilt, Rittich was tested by Mikko Rantanen, who found himself at the right place, at the right time to grab a rolling puck in the slot, but wasn't able to get off a perfect shot due to the bobbling biscuit, still the Flames 'tender having to make an important stop.
Ryan Graves opened the scoring at the 4:32 mark of the first on a play that started with a great stretch pass from defenceman Samuel Girard up to J.T. Compher, to Joonas Donskoi, to Graves for the finish, his shot finding a hole under Rittich's arm.
The shots ended up 10-9 Calgary after 20 minutes, both teams with quality chances above and beyond the lone goal.
Rittich made two huge stops in quick succession on Rantanen and Avs captain Gabriel Landeskog off a rush, while the Flames best chance was courtesy of the familiar duo of No. 13 and No. 23, Johny Gaudreau making a pass back in the slot to a trailing Monahan but Colorado goalie Pavel Francouz was able to slide and make the stop.
Oliver Kylington was whistled for the only penalty of the frame - a tripping call - but Calgary's top-end PK stood tall.
Early in the second, Rittich came up big again against Rantanen - who had beat Noah Hanifin wide and cut hard to the net - by kicking out his right pad to deny the shot.
Later, Gaudreau wired a shot from a sharp angle which Francouz looked like he thought beat him, but the puck ended up under his back as he was laid out in the crease.
Ryan's tally at 9:33 tied it up, albeit briefly.
He deftly tipped a point shot from Kylington that beat a screened Francouz - who had Lucic parked in front of him battling for position, the puck past him and bouncing back out of the net before he heard the whistle.
But a scant 31 seconds later, the homeside took the lead again, Valeri Nichushkin gathering up the rebound from a Graves shot and taking a few strides and wrapping it around the outstretched leg of Rittich.
After killing another powerplay - captain Mark Giordano called for a slash as he chased down Nathan MacKinnon on a breakaway, the Avs star shooting wide - the Flames got a powerplay of their own after Gaudreau was held by defenceman Mark Barberio.
Elias Lindholm won the faceoff, the puck going up to Giordano up at the point, who feed Matthew Tkachuk on the sideboards, Chucky taking a few strides and snapping a deadly wrister that beat Francouz short-side - who was screened by Lindholm.
The fans at the Pepsi Centre still hadn't settled back into their seats after the second intermission before Mangiapane made it a 3-2 game just 12 seconds in, beating Francouz high far-side after pressure forced a turnover in the Colorado zone.
Mangiapane came out of the corner, made a short pass to Tkachuk in the slot who passed right back and he snapped it home.
MacKinnon made it a one-goal game, spinning out of the corner and driving out into the slot and beating Rittich 3:29 into the period.
Showing just why people have been so impressed with their play, the Avs showed their resiliency, too, by tying it up on a Donskoi marker at 10:45.
The final half of the period was stellar, both teams creating a plethora of solid chances but unable to find twine.
In overtime, the Flames had the majority of good chances but it looked grim as MacKinnon cut to the net on his forehand, but Giordano made an incredible play to knock the puck away, Dube taking it and feeding Monahan who swept in behind the D and across the crease to go high far-side at 2:09.
"It starts with Gio. He made a good defensive play to break the puck up. Doobs, a little toe drag at the blueline and fed me on a breakaway. When you finish those ones, it feels good and everyone on the ice was a part of it."
On how the boys are feeling:
"I was saying earlier, we're having fun right now and we're enjoying it. When you come to the rink and you're working hard for the guy next to you, you see smiles on guys' faces and that goes a long way and that's a big part of it."
Tkachuk on the OT tally:
"I thought it was a sick play on a partial 2-on-1 by G. Doobs made a sick toe drag in the middle and Mony was showing off his speed going wide and made an unreal move going that fast with guy on him right over the good. Three great plays by three good players."
Chucky on character win:
"I just thought the way the game went and the way we were able to come back once they made it 4-4, I thought that was fun - it showed our character. Getting it to overtime, that was big for us, and getting the extra point was great."
Dube on the night:
"I don't think we got too high or low. When we get two there, I still thought we pushed the pace - just a couple breakdowns that ended up in the back of the net. But right away, we responded and we got even tighter and played a good game. It was good to get it in overtime."
Interim coach Geoff Ward:
"I said. 'We were playing well. Let's stick with the process. Just play the right way. Let's continue to be on our toes. Just have some composure with the puck.' I thought the guys did a really good job. They were resilient, they did an excellent job sticking with the process, an excellent job looking after the little details that we needed to look after. As a result, it's a well-earned win by our group."
Ward on team's run of late:
"I think it just reinforces the confidence that the guys have in each other - it reinforces the trust that you need to have with your teammates. Now, it springboards us forward a little bit. It's nice to see them get rewarded for their hard work. But as we've talked about these last couple days, when you work hard and you play with structure, then your skill gets to show. And now our skill is starting to show.
This is the Flames fifth back-to-back scenario of the season, and the second such set for the Flames in December as they will see Dallas and Minnesota on Dec. 22nd and 23rd. The Flames are currently 2-3-0 in the first game of a back-to-back situation this season ... The Flames are now 7-9-3 against Western Conference opponents, and 3-4-2 against the Central Division.
Matthew Tkachuk - Elias Lindholm - Andrew Mangiapane
Dillon Dube - Sean Monahan - Mikael Backlund
Milan Lucic - Derek Ryan - Johnny Gaudreau
Tobias Rieder - Mark Jankowski - Michael Frolik
Mark Giordano - TJ Brodie
Noah Hanifin - Travis Hamonic
Oliver Kylington - Rasmus Andersson
It's right onto the plane for a flight to Arizona, where they'll take on the Coyotes Tuesday in the second game of this back-to-back road trip. Then it's home for a date with the Maple Leafs on Thursday (click here for tickets), before rare matinee at the Scotiabank Saddledome when they host the Hurricanes at 2 p.m. (click here for tickets).