Billie Joe Armstrong Rehab: Green Day Front Man Seeks Substance Abuse Treatment after Onstage Meltdown [VIDEO]

Green Day front man Billie Joe Armstrong has entered himself into rehab for substance abuse treatment following a profanity-laden onstage meltdown at Friday's iHeartRadio music festival. Armstrong felt that Green Day's set was cut short during the popular music festival, resulting in a vulgar, guitar-smashing outrage.

Green Day representatives posted this message to fans on the band's website on Sunday:

"Billie Joe is seeking treatment for substance abuse. We would like everyone to know that our set was not cut short by Clear Channel and to apologize to those we offended at the iHeartRadio Festival in Las Vegas. We regretfully must postpone some of our upcoming promotional appearances."

Supposedly, 40-year-old Armstrong believed Green Day's iHeartRadio set was cut short in order to make more time for other big-name acts including Rihanna and Usher (from 45 minutes to 30 minutes). While flipping off the camera and smashing his guitar onstage, the "American Idiot" rocker screamed this out to the festival crowd (among other expletives...):

 "You've gotta be f##king kidding me! You're f##king kidding me. What the f##k! I'm not f##king Justin Bieber, you mother##kers...I got one minute-one minute left."

And no, Bieber was not one of the performers at the iHeartRadio music fest.

Green Day has not released what sort of substance abuse Armstrong is seeking treatment for. Armstrong was hospitalized in Italy earlier this month for an undisclosed "illness," and back in 2003 the guitarist was arrested for drinking and driving, having received a breathalyzer reading of more than twice the nationwide legal limit.

Green Day has also announced that some upcoming promotional appearances for the band's upcoming album "Uno!" (due out Sept. 25) have been canceled.

According to an inside source who spoke with Us magazine, this onstage meltdown was a wake-up call for Armstrong that he really needed to seek some professional help: "He felt bad about it afterwards. This just highlighted some of the issues he's had for a while. He reacted badly [and was] pissed in the moment."

Green Day is set to release a trilogy of albums in the next few months: "Uno!" (Sept. 25), "Dos!" (Nov. 13), and "Tre!" (Jan. 15).