The American Idiot singer plays an ageing punk in his first lead role, and The Descendants star Greer believes he has a big future as a movie star.

The actress, who plays an old girlfriend, admits Billie Joe's involvement was one of the reasons she signed on for the movie - Armstrong's second foray into film acting in two years after he appeared in 2014's Like Sunday, Like Rain.

"I wanted to work with Billie Joe Armstrong, he's amazing," she tells Press Association. "I have been a Green Day fan since forever. I thought he was brilliant and it was so fun to watch him and work with him."

And she really liked hanging out with the singer too, adding, "He's a total peach. He is such a normal guy. He loves his sons and his wife and all his dogs and just loves to play music. I thought it was such a good role for him."