Green Day Frontman Billie Joe Armstrong Enters Rehab

After a profanity-laden rant this past Friday at the iHeartRadio music festival, 40-year-old Green Day frontman Billie Joe Armstrong has checked into rehab. 

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"Billie Joe is seeking treatment for substance abuse," the band said in a statement posted to its website Sunday. "We would like everyone to know that their set was not cut short by Clear Channel and to apologize to those they offended at the iHeartRadio Festival in Las Vegas."

A rep for the band added, "The band regretfully must postpone some of its upcoming promotional appearances," supporting its new album 'iUno!', being released on Monday, September 24. 

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During Friday's festival concert, the rocker believed that the band's set was being cut short. Armstrong noticed a one-minute warning sign in the back of the arena and flipped out, going on a profanity-laden rant, smashing his guitar and flipping off the camera.

"Oh f--k this shit. I'm gonna play a f--king new song. F--k this shit. Give me a f--king break. One minute left. You're gonna give me one f--king minute?" he said after noticing the sign.

He went on to say: "Let me tell you something, I've been around since 198-f--king-8. And you're gonna give me one f--king minute? You've gotta be f--king kidding me! What the f--k! I'm not f--king Justin Bieber, you motherf--kers."

In early September Armstrong was hospitalized in Bologna, Italy, for an undisclosed illness, but recovered well enough to perform at the MTV Video Music Awards on September 6. It’s unclear what Armstrong is receiving treatment for this time around; in 2003, he was arrested for drinking and driving, receiving a breathalyzer reading more than twice the legal limit. He has acknowledged taking various drugs in the past but has said he cleaned up since having children.