Ultra 2015: Skrillex Shocks With Guests Diplo, Justin Bieber, and Diddy

Ultra 2015 just might go down in history as the most cameo-crazy edition of the festival ever.

Last night, Usher showed up for Martin Garrix’s set on the Main Stage to perform their new single, "Don’t Look Down.” And honestly, even though we joked about the possibility of a Bieber spotting, we really thought Mr. Usher Raymond IV’s surprise appearance would be the ultimate celebrity moment of this year’s fest.

But then Ariana Grande arrived at Ultra today, alongside Cashmere Cat, on the Worldwide Stage for a couple of their collabo tracks, “Be My Baby” and “Adore.”

And with the news that Bieber had joined Ms. Grande on Saturday night at downtown Miami’s American Airlines Arena for a duet of his “As Long As You Love Me”... The rumors of Biebz popping up at Ultra 2015 didn’t seem so far-fetched anymore. So tonight, when Skrillex’s festival-closing set on the Main Stage suddenly turned into a special-guest extravaganza, the whole world began to suspect that something was up.

At about 10:45 p.m., Skrill's Jack Ü partner, Diplo, jumped behind the decks with him. And then a steady stream of singers and rappers started pouring out. Most notably, there was Kiesza who performed her, Skrillex, and Diplo’s Jack Ü collaborative single, "Take Ü There."

And then Diddy bopped out, wearing a bucket hat.

Finally, though, Bieber made his big entrance, singing along to pre-recorded vocals for his own Jack Ü track, "Where Are Ü Now,” while wilin’ out with the whole mob of famous faces that had gathered to say, “See ya,” to Ultra Music Festival 2015.