Producer Bob Rock, who worked with Metallica from 1991's Black Album through 2003's 'St. Anger,' thinks the band is set up to produce a signature comeback -- though Rock says he won't be involved.

"I just don't see it happening," Rock tells Eddie Trunk. "I think they've gotta continue to move forward. I think [with 2008's] 'Death Magnetic,' they went back to their roots, which is great. And I think they've got a landmark record in them, and it's probably brewing right now."

Rock's initial self-titled project with Metallica debuted at No. 1 on the Billboard charts, eventually selling 16 million copies. Along the way, he also oversaw their bold experiment with orchestral rock. But a little over a decade later, with the release of 'St. Anger' and the controversial documentary 'Some Kind Of Monster,' Rock's influence on the band was being questioned.

A petition calling for Rock's ouster launched during sessions for 'St. Anger,' garnering some 1,500 signatures. "The criticism was hurtful for my kids, who read it and don't understand the circumstances," Rock told Billboard. "Sometimes, even with a great coach, a team keeps losing. You have to get new blood in there."

Rick Rubin took over for the return-to-form 'Death Magnetic,' though Rock says he remains on friendly terms with Metallica. "When you spend fifteen years with somebody," he tells Trunk, "and [you've] kind of gone through all the things they've gone through and I've gone through, they're a big part of my life -- period."

Metallica is continuing work on a follow up to 'Death Magnetic,' having released a new song last summer. They will headline the Reading and Leeds festivals in 2015.

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