After the teams exited the field with Calgary leading Hamilton 17-7, a stage was quickly assembled, complete with fans at the 55-yard line.
"Welcome to the new age, Canada. Here they are, Imagine Dragons," the PA announcer said by way of introduction.
The stage was only visible to one side of the stadium, but the big screen above showed the rest what was going on.
The Las Vegas-based Dragons opened with their new single "I Bet My Life," with sparks flying above the boomerang-shaped stage.
"Hello Canada," said frontman Dan Reynolds, looking lithe in jeans and a black T-shirt.
The band then launched into "Demons."
"I know we are visitors to this county but Canada has always made us feel right at home .. .Thank you for having us," said Reynolds.
The band then went "Radioactive," hammering away at a drum the size of a kids' wading pool during the middle percussive section. A smaller drum bit the dust in the finale.
Country singer Dallas Smith kicked off the festivities, playing "Tippin' Point" and "Wastin Gas" in the pre-game show.
Smith has CFL connections. The native of Langley, B.C., is married to a former member of the Edmonton Eskimos dance team
Montreal's Nikki Yanofsky performed the national anthem.
Imagine Dragons were fresh off their performance a week ago at the 2014 American Music Awards in Los Angeles where they won "Favourite Alternative Artist" and performed "I Bet My Life" for the first time live — complete with choir, lasers and pyrotechnics.
Rolling Stone called the song, which it said evoked the Lumineers, Mumford & Sons and Coldplay, one of the best moments of the AMAs.
In January, Imagine Dragons won the Grammy for "Best Rock Performance" for "Radioactive" and combined with Kendrick Lamar for a critically acclaimed Grammy mashup performance of their songs "Radioactive," and "m.A.A.d City."
The band has been good at placing its music in spots with maximum exposure. "I Bet My Life" was featured in a Sprite ad focusing on LeBron James' first game back as a Cleveland Cavalier, for example. And "Radioactive" was used in an ad for the video game "Assassin's Creed 3" and TV show "Chicago Fire."
"It's Time," was used in a trailer for the movie "The Perks of Being a Wallflower."
Imagine Dragons also features guitarist Wayne Sermon, bassist Ben McKee and drummer Daniel Platzman.
Hedley, from Abbotsford, B.C., played during halftime of the 2013 game in Regina. Saskatchewan's Sheepdogs entertained before kickoff.
The all-Canadian cast of Justin Bieber, Carly Rae Jepsen, Marianas Trench, and Gordon Lightfoot performed the halftime show of the 2012 championship game in Toronto.
Some had wondered about why the league had chosen a non-Canadian act to take centre stage at Canada's football showcase.
A look at Twitter offers an explanation.
The Dragons have 1.83 million followers on Twitter. The CFL and its nine teams have a combined 614,600.
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