Billie Joe Armstrong fell off the wagon while performing in Las Vegas over the weekend leading him to enter rehab, a family friend tells Celebuzz.

Claudia Suarez Wright, the ex-wife of Green Day drummer Frank Edwin Wright III (aka Tre Cool) confirmed Armstrong entered rehab on Monday.

What happened in Las Vegas? Claudia, whose son is Billie Joe's godchild, revealed details that led to the difficult decision to get help. "When he was in Vegas he was drinking a lot. The night of the show he had been drinking," said Claudia, adding that her ex-husband texted her yesterday about the band's ultimate conclusion.

"In Las Vegas there's a lot of temptation to drink and it's tough to be around when you're fighting against it," she said. "They have a new album coming out and it's a demanding lifestyle. It's very difficult."

According to Claudia, the famed frontman had been sober for over a year. more on this story