Watch Justin Bieber, Diplo & Diddy Join Skrillex During Ultra Headlining Set

Jack U
Chelsea Lauren/WireImage

Skrillex and Diplo of Jack U perform at the HARD summer music festival at Whittier Narrows Recreation Area on Aug. 2, 2014 in Los Angeles, California. 

The L.A. DJ and his Jack U teammate Diplo took the stage with a slew of stars from their recent album.

After a weekend of surprise guests that included Usher and Ariana Grande, Skrillex topped off his headlining set at Miami's Ultra Music Festival with Justin Bieber, Diplo, KieszaDiddy, and South Korean vocalist CL of 2NE1

Ultra has a long history of surprise guests. In 2012, Madonna made an unforgettable cameo during Avicii's headlining set in which she asked the audience how many of them had seen molly (disappointing deadmau5, among others). And last year, Diplo brought out Riff Raff, Wacka Flocka and Sean Paul. This year's crashers were teased throughout the weekend by the festival's main stage MC, who also announced that Ultra will be expanding to Singapore, adding to its roster of events in Croatia, South Africa and Japan. 

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Of course, these particuar guests weren't all that surprising. Skrillex and Diplo have ramped up joint appearances over the last year as the EDM super-duo Jack U, and last month released their eponymous debut LP which features collaborations with Bieber and Kiesza. And CL, who appears on Skrillex's 2014 album Recess, performed their track "Dirty Vibe" along with her own K-pop single "MTBD" over Diddy's "It's All About the Benjamins" beat. It was widely rumored that Missy Elliott would be appearing thanks to her buzzworthy remix of the album's lead single, "Take U There," but hip hop fans got Diddy instead. The rapper's appearance doesn't make much sense aside from the fact that he's a fixture on the Miami Music Week party circuit, hosting a lavish pool party at his Star Island mansion during festival weekend.  

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On Saturday, Usher joined Martin Garrix on stage to perform their new track "Don't Look Down," and Ariana Grande made a cameo during Cashmere Cat's Sunday set for their single, "Adore You," which is currently climbing the Billboard Hot 100. The festival also hosted a stage curated by Skrillex's label, OWSLA, which welcomed What So Not.