Ariana Grande closed the Billboard Hot 100 Music Festival Saturday night with a healthy dose of star power.

Grande brought out rapper Mac Miller to deliver his verses on her hit “The Way,” part of the day’s biggest production.

Her slinky version of the new single “Into You,” backed by her dance troupe and full band, made it clear who the evening’s biggest star was, even though earlier it seemed the Nikon at Jones Beach Theater crowd couldn’t get enough Fetty Wap.

Even before the New Jersey rapper took the stage, he caused a commotion just walking back to his dressing room. Fans rushed to the walkway to touch the “Trap Queen” star, who high-fived everyone he passed.

The festival, which wraps up Sunday night with superstar DJ Calvin Harris, set records for both single-day and two-day attendance in its debut last year, bringing in more than 40,000 in its two-day run. That record will stand, as Live Nation, which produces events at Nikon at Jones Beach Theater, decided to cap attendance at 15,000 each day for a less congested, more enjoyable festival vibe.

The plan worked, as fans had room to dance along to the Drake songs booming out of the Amp Radio tent on the plaza and could stay hydrated without waiting in long lines on the stifling day.

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Focusing on up-and-coming acts this year also paid off. Alt-country rockers Josiah & the Bonnevilles opened the Sun Stage with a stunning set about singer Josiah Leming’s Appalachian roots and failed relationships. Though the quartet only has the “Cold Blood” EP out, they could grow into one of the year’s breakout stars. With songs like “Can You Hear It” and “Long Gone,” they could be on their way to becoming the next Mumford & Sons.

Rappers Rae Sremmurd delivered an energetic set, drawing mostly from their new album “SremmLife 2,” though Slim Jxmmi and Swae Lee got the packed Sun Stage bouncing early to “No Flex Zone.”

British pop-soul singer Nathan Sykes was also impressive early on, with the sleek throwback soul of “Kiss Me Quick” and a dramatic, rocking version of Shawn Mendes’ “Stitches.”

Singer-songwriter Rachel Platten did a surprising cover as well, warming up Swedish House Mafia’s “Don’t You Worry Child” before delivering a rousing version of her anthem “Fight Song.”

“It means the world for me to be here today,” said Platten, a longtime veteran of the New York club scene.