Justin Bieber Song, "Dr. Bieber," Leaks (Listen)

The tune addresses "Bieber Fever."

Justin Bieber's new tune, "Dr. Bieber," has leaked online.

The lyrics address "Bieber Fever" -- and he raps! (His has Tweeted his alter ego rap name is "Shawty Mane.")

REVIEW: Never Say Never

"Bieber Fever spreading rapidly and it's uncurable. I repeat uncurable/I got a PhD, I don't need a fake ID/ You females know of me, I'm so sick with no IV/ J-U-S-T Bieber Fever on the street, time to realize I'm the beast."

PHOTOS: Outtakes from Justin Bieber's THR cover shoot

"This is not a cold, not a flu, not a sickness. This is good and doesn't hurt to get this...You were never cured and you never will regret this."

PHOTOS: Justin Bieber's Never Say Never L.A. premiere

Bieber's rapid rise to success, backed by Scooter Braun, L.A. Reid and Usher, is chronicled in the new issue of The Hollywood Reporter.

His 3D movie, Never Say Never, hits theaters Friday.