Falling square in the middle of Midland’s new album “Let It Roll,” the song “21st Century Honky Tonk American Band” is in some ways a distillation of this Grammy-nominated Dripping Springs trio’s identity. Starting as a classic minor-key outlaw romp (name-checking Waylon Jennings, even) propelled by a sharp-cutting guitar riff, it shifts briefly to a major key in the chorus, allowing a touch of modern pop country to seep in before that riff returns.

And then: Three minutes in, all bets are off as the beat suddenly slows way down. Lead singer Mark Wystrach reaches to the high end of his register with what feels like an emotional reckoning. “I know I’ve been away too long,” he laments, “’cause I’m the same, but they’ve all changed.” It’s a remarkable musical moment that cuts against all preconceptions of country radio, even as it echoes back to a similarly dramatic left-turn midsection the Bee Gees wove into their mid-1970s top-5 smash “Nights on Broadway.”

In summary: Yes, Midland is a honky-tonk band, at its core. And they readily acknowledge the modern realities of country music in the 21st century. But if you try to contain them within either of those bounds, they’re likely to surprise you.

RELATED: Our Review of Midland's new album

“There’s an element to us, and there always will be, I think, that’s a little bit askew — like that part in that song,” Midland guitarist Jess Carson says. “That’s very important to us, just to be able to do what we want to do.”

The trio gets what may be its highest-profile Austin airing to date on Saturday when they play a free show on the LBJ Library Lawn just before the Texas Longhorns take on the LSU Tigers in what’s arguably the University of Texas football program’s biggest home game of the decade. It’s part of the “Longhorn City Limits” series of pregame concerts that began last year.

“Let It Roll” came out two weeks ago and this week entered the Billboard country albums chart at No. 1, a first for the band. It follows a self-titled 2016 introductory EP and the band’s 2017 debut album “On the Rocks,” which quickly made Midland one of the hottest new acts in mainstream country music. The catch being that they’ve managed to find a place within that mainstream while playing music that doesn’t really toe the Nashville line.

It’s one of the reasons Carson moved to the Austin area eight years ago, before he teamed up with Wystrach and bassist Cameron Duddy to form the band that earned a Best Country Song nomination for “Drinkin’ Problem” at the 2018 Grammys. “Nashville feels too under-the-magnifying-glass to do what you want,” Carson says. In Austin, he adds, “we were left alone for the first two years to create what was in our heads.

“When you care about music history, there’s so much to draw from here. And there’s this residual level of musicianship here — a standard and a spirit that permeates this whole area. It influences everything that you do here. You can’t help but be influenced by it.”

A LOOK BACK: Review of Midland at ACL Fest 2017

It’s not that they avoid Nashville. Much of “Let It Roll” was recorded there, and the trio co-wrote most of the album’s songs with well-traveled Nashville songwriters including Josh Osborne, Shane McAnally, Bob DiPiero and Rhett Akins. Their label, Big Machine, is based there.

But Midland’s ties to Texas, where they formed after first getting to know each other in Los Angeles, are essential to how the band evolved. It started with 2013 sessions at Sonic Ranch, a renowned studio in the El Paso suburb of Tornillo, that produced songs including “Fourteen Gears,” a sweetly swaying classic country tune that was written by Carson, Wystrach and … David Garza?!

Yes, the eclectic and outlandishly talented songwriter and producer, who first rose to prominence as an Austin teenager in 1990 with the pop trio Twang Twang Shock-A-Boom before going on to front the Love Beads and Dah-veed, played an integral role in Midland’s origins. You can even see him in an early video for “Fourteen Gears” that went up on YouTube in 2015, before the band had a record deal. (A freshly recorded version of the song is on the new album.)

“I met David around the time that I first moved to Austin, about eight years ago,” Carson says. “He was producing songs I was cutting over at Public Hi-Fi, Jim Eno’s studio. He was bringing in this cast of Austin people and just doing his own weird David stuff. We just hit it off, and I was so impressed by him.”

Garza, who'd recorded at Sonic Ranch for years, brought the group out there and remembers those early sessions well. "It was one of those rare moments where you’re there for the beginning of something," he said. "And then you see it actually work."

It reminded him, in some respects, of Twang Twang's early days. "There’s something really magic about trios," he said. "Something probably tugged at my heart about those three guys, and I could see a little bit of my own story in their story as well.”

“We were exploring the sound,” adds Wystrach, “and it really came together at Sonic Ranch with David. There was this magical moment that occurred — many moments over that span of time, but something congealed us. We grew a lot as collaborators, as songwriters, as brothers really on that trip. Not to sound corny, but there was something magical about that session, that whole experience.”

It’s a spirit that has carried over to newer compositions like “21st Century Honky Tonk American Band” and its wholly unusual bridge. “Those chords were just floating around, and we caught onto it,” Duddy says. “We just took our liberties of whatever came, and if it sounded good, we went with it. Plus, Bob DiPiero and Rhett Akins (co-writers on the tune) had bought in already that we weren’t trying to write a radio song.

“That’s a cool part of the song too, because it kind of talks about the less-badass part of living on the road, and more of the emotional aspect of it. The other side of the token.”

READ MORE: Our 2016 interview with Midland's Jess Carson