Green Day producer Rob Cavallo has hinted that Green Day may be forced to cancel more live shows due to Billie Joe Armstrong’s stint in rehab.

The frontman of the pop-punk trio checked himself into a treatment centre for substance abuse last month following an onstage meltdown at the iHeartRadio Music Festival in Las Vegas.

And now the chairman of Warner Bros Records, who worked with the band on their latest album, 'Uno,' told Rolling Stone that he’s not sure whether he’ll be ready to return for their upcoming Novermber shows:

“His rehab is no joke. He's under medical supervision for a while to get him clean.

"His doctors are still evaluating. All I can say is I don't know if we'll see him before or after Christmas. It's basically undetermined when he'll be back."