On Sunday night, the Calgary Flames will host the Philadelphia Flyers at the Scotiabank Saddledome for the final time.

While the Flames and many other teams from out east don’t have horribly extensive histories – primarily because they don’t play often in-season and rarely meet in the playoffs – the Flyers are different.

The first playoff series in franchise history, in 1974, featured the Atlanta Flames being swept by the Flyers in the first round. At the time, the NHL had just 16 teams. Atlanta, in their second season, finished fourth in the West Division, and were matched up against the Flyers, the West Division winners.

The Flames lost every single game – 4-1, 5-1, 4-1 and 4-3 – and were eliminated in four games. The Flames never held a lead at any point in the first three games. In Game 4, they blew a 3-0 lead and were eliminated in overtime off a Dave Schultz goal. The Flyers went on to win the Stanley Cup that year.

Anyway, the Flames relocated from Atlanta to Calgary in May 1980… too late for the league to realign the divisions or alter the schedule for the 1980-81 season. As such, the Flames remained in their prior division, the Patrick Division, and had a schedule chock full of their divisional rivals from the Atlanta days: Washington, the NY Islanders, the NY Rangers and Philadelphia.

In their first year in Calgary, the Flames qualified for the Stanley Cup playoffs. At the time, a league-wide seeding system was ruled, and the Flames swept Chicago in a best-of-five preliminary round series – the first series win ever for the franchise – and their reward was a rematch with the Flyers.

In their first-ever best-of-seven playoff series, the Flames actually eliminated the Flyers in seven games, earning a measure of revenge for 1974’s sweep. After being shut out in Game 1 by the Flyers, the Flames won each of the next three games by a single goal to push Philadelphia to the brink of elimination, only for the Flyers to battle back to force a decisive seventh game. The Flames beat the Flyers by a 4-1 score in Game 7 at the Spectrum to advance. Guy Chouinard led the Flames with nine points against Philadelphia, while Willi Plett posted 61 penalty minutes in the series. Plett’s 31 penalty minutes in Game 5 was a playoff game franchise record that was only surpassed by Deryk Engelland in that 2015 game where he fought two Vancouver Canucks at once (and received 42 PIMs for his troubles).

(Just a single player remained from the 1974 team: forward Eric Vail, the franchise’s all-time leading scorer, who posted zero points in the first six games of the Flyers series and was scratched in favour of Bert Wilson for Game 7.)

The Flames ended up losing in the third round to the Minnesota North Stars, but the 1981 playoffs represented a massive breakthrough for the Flames franchise, and a tremendous spring that helped Calgarians fall in love with their long-awaited NHL team. Despite their rivalry feeling a bit cool these days, the Flyers – and that 1981 series – remain a pretty important part of Flames lore.