Green Day’s Billie Joe Armstrong checks into rehab after Justin Bieber tirade

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There's something about Justin Bieber that just drives Billie Joe Armstrong crazy. On Sunday, the Green Day frontman checked into rehab for an undisclosed "substance abuse" issue two days after having a massive meltdown onstage at the iHeartRadio festival, during which he shouted, "I'm not f--king Justin Bieber!" after the band's set was cut short … even though the "Boyfriend" singer was not even there. Armstrong's rant was ignited by a "1 minute" warning that flashed on a teleprompter in the middle of their set, instructing the "American Idiot" rockers to wrap it up.

"You're gonna give me one minute?!" he yelled into the mic. "I've been around since f--king nineteen eighty f--king eight, and you're gonna give me one minute?! You've gotta be f--king kidding me! I'm not f--king Justin Bieber, you motherf--kers!" … and then Armstrong, 40, smashed his guitar to pieces.

WARNING: The following video contains explicit language

The 18-year-old singer seems to be a touchy subject for Armstrong. According to Howard Stern, when Green Day appeared on "America's Got Talent" on September 13, a pre-recorded performance by Bieber played before the band hit the stage and Stern says he noticed Armstrong shaking his head in disapproval as he watched backstage.

It's unclear why Armstrong dislikes Bieber so very much. Maybe one of his sons (Joseph, 17, and Jakob, 14) is a fan and has played "Baby" a few too many times at home?

Green Day has postponed upcoming appearances as Armstrong seeks help for his issues. The band is releasing the first of three new albums, Uno, tomorrow.

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