Megadeth front man Dave Mustaine has said in the past that Ellefson was on Metallica's radar after the death of Cliff Burton in 1986.
But recently Ellefson revealed his name also came up when Metallica was in need of a bass player between 2001 and 2003.
Bassist Jason Newsted left Metallica in 2001, and the band was without a fourth member until after completing its St. Anger album and hiring Robert Trujillo in 2003.
When asked in a recent interview with The Metal Voice whether he was ever approached by Metallica around the turn of the century, Ellefson revealed that while he was never called to audition, "I know that there was a conversation about considering me. I know Lars [Ulrich] and Dave had chatted, 'cause [Metallica] were putting their short list together."
Megadeth disbanded in 2002. That same year, Ellefson sued Mustaine for $18.5 million in unpaid merchandise earnings and publishing royalties. (Ellefson rejoined Megadeth in 2010.)
Ellefson added that he's sure he would have shown up at the audition if he was invited.
"I'm a fan of theirs and friends with them, and I would be there to be of service with them in whatever way, but they, I think, made their decision right around the time when Megadeth had disbanded in 2002," he said.
It's unclear if the timing was wrong or if Metallica ultimately decided it didn't want to share two members with Megadeth. Still, it seems the episode inspired Ellefson's curiosity, and he eventually sat down to figure out some Metallica songs on the bass.
"I did one day, and I was like, 'Oh my gosh!' These songs are so different than Megadeth," Ellefson observed. "Their riffs and where James puts the phrasing of his vocals over the top of his riffs is so different from how we do it in Megadeth. And I found it kind of fascinating, because, here we are, the two bands — and obviously Dave having played in Metallica in their early years — how their sound really developed and transitioned over the years and how Megadeth's sound ... developed..."
Mustaine told CBS in 2011 that he was "concerned" he was going to lose his bassist to his former band back in 1986.
He added that he didn't think he "would have done well" if Ellefson jumped ship to Metallica in the '80s.
"Fortunately for me, I think those guys took that into account and just said, 'Let's find someone else,'" Mustaine recalled.
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