Looks like this Billie Joe Armstrong in rehab thing isn’t a stunt…

Metallica has been announced as the Saturday, October 27th headliner at the 2012 Voodoo Music Experience in New Orleans, according to a press release. The band is subbing for Green Day, who had to drop out of the event when frontman Billie Joe Armstrong went into rehab late last month. It will be Metallica's first appearance at the annual Big Easy festival, with drummer Lars Ulrich saying, "Our good friends and fellow Bay Area residents Green Day had to unfortunately cancel their plans to be there, so we are more than happy to fill in for them in our own unique way. We're hoping we can fill those very large shoes and do them proud."

The rest of the lineup for the Voodoo Experience -- which starts on Friday, October 26th and ends on Sunday, October 28th -- includes Neil Young & Crazy Horse, Jack White, Justice, Skrillex, AWOLNation, Nas, the Avett Brothers, the Silversun Pickups, Gary Clark Jr. and many more.

Meanwhile, Green Day producer Rob Cavallo -- who's also the head of the band's record label, Warner Bros. -- has told Rolling Stone that Armstrong's road to recovery may take longer than anyone anticipated.

Armstrong sought treatment for substance abuse last month following his profanity-filled meltdown at a radio festival in Las Vegas on September 21st.

Cavallo revealed, "His rehab is no joke. He's under medical supervision for a while to get him clean."

Although Green Day is scheduled to start a world tour on November 26th in Seattle, Cavallo added that that start date could be in jeopardy. He explained, "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."

Bassist Mike Dirnt told BBC Radio One last week that all promotional appearances for the band were on hold, saying, "We had to put the life of our friend in front of everything."

The bass player revealed that he hasn't seen Armstrong "in weeks" since the frontman entered rehab, the longest stretch in the past 20 years that he has not spent time with his bandmate.

The first of Green Day's three new albums, Uno!, was released on September 25th and debuted a week later at Number Two on the Billboard album chart, selling 139,000 copies in its first week. The second disc, Dos! is expected to arrive on November 13th, with Tre! due out on January 15th.

Rock 101 question: What’s the name of the first single Green Day released from the trilogy of albums due out this year?

Rock 101 answer: Oh Love.

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