Metallica were on the brink of calling it quits before receiving a phone call from the Rolling Stones asking them to open for the band.
The Enter Sandman rockers planned to retire in 2004 due to constant fall-outs and hard living. The same year, drummer Lars Ulrich famously pulled out of a performance at Britain's Download festival due to anxiety issues.
Speaking about the difficult time, Lars explained the band made the decision to carry on when the Stones called a year later and asked if they'd be interested in teaming up for a set of live shows.
"That period (2004) certainly wasn't easy for us and, since then, we have learned boundaries and where our breaking points are," he told Britain's The Sun newspaper. "That was the last time we had a real break - we haven't shut down the band in 14 years, but we disappeared then for about a year.
"And then the Rolling Stones called us up and said, 'Come and play some shows with us in California,' and we sort of agreed - you're not going to say no to the Stones - so that was it."
Explaining how the phone call inspired him, frontman James Hetfield, lead guitarist Kirk Hammett, and bassist Robert Trujillo to carry on, he added: "It gave us the way to start it back up again. Whether you're a team in an office or a bunch of dudes in a rock and roll band, at some point people have to figure out how to get along and work as a team.
"If you don't care, it's easier to walk away, but fortunately we cared enough about Metallica on behalf of ourselves and the fans to figure out a way to make it function. I'm happy that we did."
Metallica performed a triumphant gig at the Etihad Stadium in Manchester, England on Tuesday, and donated $51,000 (£40,000) to local homelessness charity Coffee4Craig ahead of the concert.
