Fuse's Esteban Serrano caught with Mac Miller at Bonnaroo 2012 and learned all about the always-busy rapper's recent collabo with Justin Bieber and his upcoming EP with Pharrell. 

"Scooter [Braun, Bieber's manager] reached out to me and said, 'Justin is about to do this 'Boyfriend' remix, we want you to be on it,'" Miller tells us. "I was like, 'Alright, let's go.' He sent me the beat, I did the verse, then 2 Chainz got on it, and they put Asher [Roth] on it as well, so it was just dope. 

"It's crazy to see how big that kid really is. Justin is a whole 'nother level of famous. I've never seen that type of thing happen to my Twitter before," Miller says about being connected to Bieber via Twitter. "I got 40,000 followers that hour."

Miller also talks about his upcoming collaborative project with Pharrell. "We talked and we decided we're going to do this EP, Pink Slime, and bring our worlds together," Miller says. "I'm a huge fan of everything he does, and he's in support of what I'm doing. He's not just a believer in just how big this is, he's a believer in my potential of creative music that we can make together."

For the full interview, watch the video above. And head over here for our complete coverage of Bonnaroo 2012, including interviews with performers, photo highlights and news about the fest's biggest surprises.