Shawn Mendes is sexy, and he is also 6-foot-2-inch glass of 2 percent milk.

Shawn Mendes is sexy when he pulls up his sleeves. He is sexy when he brushes his hair back. He is sexy when he touches his ear monitor, when he tells someone in the crowd he is going to fling a guitar pick at them, when he bites his tongue between his teeth and when he sweats more than a Gatorade commercial.

All that swoon-worthiness is worth mentioning, because for the second-weekend Sunday sunset slot, ACL Fest mixed it up a little with a bonafide teen idol. There’s been radio-ready hunks like Hozier and Vance Joy in that schedule block before. But the “Stitches” singer was just about the cleanest cut you’d hope to find in Zilker Park, singing politely amorous songs all while looking like he might hand you a pamphlet about our Lord and Savior.

Mendes is a guy who sings about a girl who takes him places that ruin his reputation, just so we’re all on the same page about the image. Ricky Nelson in skinny pants, David Cassidy with au courant black-ink tattoos, a Jonas Brother run through a pasta press to stretch him out a little bit.

GALLERY: Pictures of Shawn Mendes (and the girls he made cry) at ACL FEST

And boy, did Mendes do his job. Playing the Honda stage, the Canadian with the curls poured his heart out from behind a rotating cast of guitars. He hit the marks, like running down the aisle of the crowd to high-five the screaming fans, or looking up to make eye contact — with no one, with someone, with anyone — on lines about kissing.

Mendes sang those lines with consistency, if not imagination. The setlist called for sensitive soul, neck veins popping, some emotions catching in his throat. His well-packaged pop made you feel dizzy with fresh love, if you let your id take over, or able to climb any number of mundane mountains peaking in your brain. Not with any sense of lyrical or stylistic specificity, of course. Sort of like how Kix are good and fill you up, but they’re still not Reese’s Puffs.

Mendes’ teeth, though, are remarkable.

The easy groove and falsetto of “Lost In Japan” put a little AM radio into the mix. The end-credits triumph of “In My Blood” couldn’t be ignored, especially when everyone around became so obviously affected. One imagined what made each person in the crowd — young, old, male, female — feel like giving up, as Mendes laid his own fight against anxiety bare (but not too bare).

A cover of Frank Ocean’s “Thinkin Bout You” was a welcome curveball, hinting at a deeper end yet to come in Mendes’ pool. At least the song winked at the singer’s own good taste. The set’s penultimate number, a cover of Kings of Leon’s “Use Somebody,” maybe less so.

But if you wanted prodigy, St. Vincent played just across the park an hour later. Mendes, the definition of appealing, provided a safe harbor at 6 p.m. A crescent moon hung in the sky. Young fans packed to the edge of the pit, starry-eyed. No harm in a little swoon every now and then.

ACL Fest 2018: See all our coverage (plus the dates for next year)