“American Idiot is a rock opera. But I was very self-conscious about it,” Green Day’s Billie Joe Armstrong told Rolling Stone’s David Fricke. “I didn’t want it to come across as pretentious. Someone said, ‘What is the influence?’ I said, ‘This record has more in common with Rocky Horror than Leonard Cohen.’ ”

Armstrong might have been skittish about American Idiot’s theatrical leanings five years ago, but with the album a Grammy-winning, blockbuster-selling success and a second punk opera under the band’s belt — this year’s 21st Century Breakdown — he’s a little more comfortable with the idea. In fact, with the American Idiot musical underway, he’s letting his appreciation for Broadway hang out a bit more. “After we did the first concert version of the libretto — with these 12 actors and singers, performing the whole thing for the band — we all went out afterwards for dinner,” the show’s director, Spring Awakening’s Michael Mayer said. “I don’t know why, but as a certain point, Billie and I were sitting across from each other, singing a song together from Gypsy. It was hilarious.”

Mayer reveals some details about the musical, which premieres September 4th at the Berkeley Repertory Theater — including how the album’s songs will mingle with B sides and Breakdown tracks — and Armstrong talks about how he was first drawn to Spring Awakening (I remember seeing that and going, “Did I write that?”) in our behind-the-scenes story:

• The Birth of Green Day’s “American Idiot” Musical

Related Stories:

• Green Day’s Buildup to the Breakdown
• Green Day’s Hometown Throwdown: “21st Century Breakdown” Onstage in Oakland
• Green Day’s “American Idiot” Musical to Debut September ‘09