It's widely known that the beat which eventually became Big Sean's E-40-featuring smash hit, "IDFWU," was originally supposed to go to Justin Bieber. (According to DJ Mustard's collaborator-turned-legal combatant, Mike Free, it was made as a response to Iggy Azalea's "Fancy," which Mustard felt had bit his sound.) And while that track obviously stayed within in the hip-hop sphere, Mustard has found a way to branch out after all. According to Idolator, the producer took time out of his London Wireless Festival schedule to reveal that he's working with Britney Spears. I haven’t told nobody yet," the super star producer said, "but I’ve been in the studio with Britney Spears." He then added the ambiguous "It’s harder than hard—it’s a movie.”

Mustard's breakthrough hit was Tyga's "Rack City," a minimal hit from 2011 that vaulted each to the forefront of mainstream rap. Since then, Mustard has refined and honed his sound; often called ratchet music, it's an update on Bay Area rap that strips hyphy to its core elements. While the sound has dominated Top 40 rap for some time now (sometimes in tandem with maximalist, Chicago-style trap), its best full-length iteration came early in 2014. My Krazy Life, YG's startling Def Jam debut, rode beats crafted by Mustard and his disciples to popular and critical acclaim. As for Spears, the most recent of her eight studio albums is 2013's Britney Jean; she remains one of the highest-selling pop stars of all time, though her recent Iggy Azalea collaboration, "Pretty Girls," failed to gain traction.

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