– It showed up the moment the crowd starting bouncing up and down furiously to the opening song, “Takin’ a Ride.” It happened again when fans yelled out, “Open wide!” and all the other bratty lines in “Tommy Gets His Tonsils Out.” And again when “Little Mascara” bled straight into “Left of the Dial.” Maybe the best instance came toward the end, when they played “Swingin’ Party” by request from their ailing pal Slim Dunlap.

Magic. That’s what it was, pure and simple. An abundance of it spilled from the stage during the Replacements’ 75-minute set Sunday in Toronto, the legendary Minneapolis band’s first of three reunion gigs over the next month.

No one doubted how much excitement there would be surrounding the quartet’s first shows in 22 years. Plenty of people, though, questioned how well the legendary Minneapolis band might pull off the reunion.

The uncertainty was certainly valid. Frontman Paul Westerberg hasn’t played a real show in nine years. Two replacement Replacements — drummer Josh Freese and guitarist David Minehan — had to be called up to round out the band, making it only a half-original lineup. Even in their heyday, the ’Mats were notoriously erratic as a live act.

Add to those challenges the fact that they had to follow bombastic, high-energy punk gurus Iggy & the Stooges to the RiotFest stage on Sunday, which you wouldn’t wish upon any band, much less an inactive one.

Westerberg, 53, didn’t need any time to dust off the cobwebs, though. After “Takin’ a Ride,” he and the band impressively tore through a bunch of similarly high-velocity, lowbrow nuggets off their earliest albums, also including “I’m in Trouble,” “Favorite Thing,” “Hanging Downtown” and “Color Me Impressed” (in that order). The singer/guitarist smiled and snarled his way through them, reiterating the snotty but tender-beneath-it-all charm that made him one of rock’s favorite outcasts.

It wasn’t until he slowed things down a few songs later for “Androgynous” that Westerberg’s armor cracked. He forgot the lyrics mid-tune, which soon happened again in “I Will Dare.” That smile turned to a smirk, though, as if fans were getting some of what they bargained for. Bassist Tommy Stinson — the other original Replacement — couldn’t offer any help when asked, which only added to the bandmates’ amusement (Minehan actually got “I Will Dare” back on track). At least in a small dose, that old imperfection felt like good medicine.

Stinson, Minehan and Freese were near-perfect all night. Freese especially provided a spark, delivering “Love You Till Friday” with loose abandon while precisely hammering the pre-encore finale “Bastards of Young.” One of the tightest, rowdiest moments for the quartet came in the first of two cover songs, “Borstal Breakout” by British punk pioneers the Sham 69. The second cover, “Everything’s Coming Up Roses,” which kicked off the encore … not so rosy.

As a lot of legendary bands do upon reuniting, the Replacements leaned heavily on their earlier material. They played just one song (“Achin’ to Be”) from their 1989 album “Don’t Tell a Soul” — but not their Canada-evoking radio hit “I’ll Be You.” And only one track from 1991’s farewell disc, “All Shook Down,” made it into the set (“Merry Go Round”).

The older tunes suited the RiotFest’s punky vibe, and it brought the band back to where it all started before members fell out and the strains of the music biz set in. But that’s probably overthinking it. It really just seemed like the guys wanted to have fun. Those particular songs fit that bill best — especially when played well, not sloppily. Westerberg and Stinson seemed as pleasantly surprised as anyone that they came off as well as they did.

We all knew how excited Replacements fans would be over these reunions. (Next up: the RiotFests Sept. 15 in Chicago and Sept. 21 in Denver.) Few would have predicted that the band members themselves would seem equally excited. Now let’s just hope they can maintain the enthusiasm long enough to get us a show back home.