Is it too soon to classify bands from the ’00s as classic rock? Because that’s certainly what Saturday’s pairing of the Black Keys and Modest Mouse at Target Center felt like.

Though they presented very different brands of rock — bluesy and crunchy in the Keys’ case, arty and nervy on MM’s end — the tour partners harked back to that seemingly long-gone era when guitar-driven, non-electronic bands still had a good shot at commercial radio play and the Billboard charts. Adding to the nostalgia factor, they each also took a long break from touring and have gone five years between records.

Always an inconsistent live act — but impressive when they’re on, like at Rock the Garden 2015 — Modest Mouse showed the rust and raggedness of being off the road.

Still without a new LP, froggy voiced frontman Isaac Brock and his crew never quite found their groove in their 45-minute set, even with two drummers in tow; or maybe that added to the discombobulation. Brock himself also never seemed to find the right positioning of his guitar pedals. He spent a lot of time between songs crouched over fiddling with his gear.

There were assorted bright spots, though. Brock & Co. started off with a bombastic kick in “Dark Center of the Universe” and prompted a singalong two songs later with the 2004 hit “Float On.” They ended strong, too, with the ferocious new single “Poison the Well” — reason to be optimistic for a more vibrant comeback after this tour.

The Black Keys, conversely, sounded ready for their return and refreshed by the time off. Singer/guitarist Dan Auerbach and drummer Patrick Carney shared sly, satisfied miles throughout their 90-minute set as if they were back in the basement in Akron, Ohio, starting all over again.

The duo’s newly expanded five-piece tour lineup, meanwhile, sounded like it’s been in action for many years instead of just a couple weeks. New guitarist Andrew Gabbard and his bassist brother Zachary Gabbard actually opened for the Keys across the street in 7th St. Entry in 2003 with their old band Thee Shams, so no surprise of the instant chemistry.

Auerbach and Carney reached back to those early years just enough to appease any of the 11,000 fans who might’ve been among the 200 at the Entry.

“Thickfreakness” and “10 a.m. Automatic” were both dropped in the middle of the set. With the extra guitarists, Auerbach was freed up to play an extra-manic solo in the latter tune. He and Carney also revived their old stop-and-go, raw-boogie synchronicity in “Your Touch” and the slower-grooving, murderous nugget “10 Cent Pistol.”

They also played just the right amount off their new album, “Let’s Rock,” to make a good case for it. “Tell Me Lies” came off like a coolly hazy blues howler reminiscent of early Fleetwood Mac. Playing under a giant electric chair in the encore (based off the new LP’s cover art), they seemed to add extra, ahem, sizzle in a slowed-down “Lo/Hi.”

Like your typical classic-rock show, though, Saturday’s set centered on the songs fans wanted most: namely, songs off their 2010-2011 albums “El Camino” and “Brothers,” which were offered in droves. In fact, they only left room for one song off 2014’s record “Turn Blue” (“Fever”).

“Gold on the Ceiling” and “Howlin’ for You” — each seemingly tailor-made for sports arenas — truly had fans howling during the first half of the set, while “Everlasting Light” dazzled under mirrorball-style spinning lights. The darker, moodier epic “Little Black Submarines” then made for a powerful climax before the whammy-bamming pre-encore finale “Lonely Boy.”

“It’s good to see you again,” Auerbach said with earnestness near show’s end. He actually said almost the exact same thing at the start, too. Nothing wrong with a rock ’n’ roller repeating themselves once in a while, though, so long as they mean it.