J/Producer Andrew Taggart of The Chainsmokers performs with special guest Desiigner during the 2016 Austin City Limits Music
C Flanigan/Getty Images

The Chainsmokers have held the No. 1 song in the country for over a month now with "Closer" and, boy, they made sure to act like superstars at the top of the world with their set at Austin City Limits Fest 2016 that included surprise guests, live song premieres and a general sense that were going to 100 percent enjoy the moment.

Andrew Taggart and Alex Pall kicked off their set just as the sun was setting over Austin's Zilker Park, bringing fun remixes of Kanye West's "Love Lockdown" and KISS' "I Wanna Rock N Roll All Night." But the massive crowd was clearly here for Andrew and Alex as they gave whoops of approval the moment they heard the initial beats of "Roses"—the duo's breakout smash from last year—singing along to the "Say you'll never let me go" hook. 

Andrew Taggart later addressed the crowd, telling them "we have this new song out called 'All We Know'" and brought its featured singer Phoebe Ryan for the song's first live performance. Taggart and his green-haired guest sang atop the mini-catwalk the band had onstage and delivered a short-but-memorable performance of the future hit.

DJ/Producer Andrew Taggart of The Chainsmokers performs with special guest singer Phoebe Ryan during the 2016 Austin City Lim
C Flanigan/Getty Images

The guys continued with a mix of their tunes ("New York City," "Kanye"), old- and new-school favorites (Third Eye Blind's "Jumper" and Kungs & Cookin' on 3 Burners' "This Girl"), but they knew everyone was craving to hear "Closer" and it was expected they'd end the show with it. When the Halsey-featuring smash finally did arrive less than 15 minutes before their time slot ended—and not before the duo explained that they wrote it in Texas after being inspired by Blink-182Taking Back Sunday and Dashboard Confessional—the crowd obviously lost it. 

What we didn't expect was for the performance to get even wilder as Desiigner (who Fuse spotted hanging out in the backstage artist area earlier in the day, despite not officially on the ACL bill) made a surprise guest appearance, delivering "Panda" for the already turned-up crowd. Desiigner fit right into the Chainsmokers' party, at one point dropping his microphone off the mini-catwalk (and never going back to get it) and savagely ripping off his tank top. 

Before the set officially closed, Andrew and Alex brought back Desiigner and Phoebe for a crowd selfie atop the stage—a smart moment to capture as it'd be tough for them to feel anymore like superstars than they were right in that moment. 

Keep up with all of Fuse's on-the-ground coverage from ACL 2016 right here and watch The Chainsmokers tell us about their mentality when creating festival sets below: