Earlier this week, Glasto organiser and founder Michael Eavis' told The Bristol Post that Saturday's headlining act are "one of the biggest-selling bands in the world at the moment" - with the full line-up expected to be announced at the beginning of May.
His comments caused many to start speculating who would be taking to the event's famous Pyramid Stage, with the likes of Prince, David Bowie and even One Direction being thrown in the mix.
However, The Sun has reported that Metallica will soon be confirmed as the final headliners - with 'contractual reasons' behind why it's taken so long to make the announcement.
Gig Wise also suggests that the thrash metal rockers were previously revealed as a 'UK exclusive' for Sonisphere Festival, meaning their Glasto stint would contradict this statement.
However, drummer Lars Ulrich has made no secret of his desire to top the bill at Worthy Farm, telling MTV News UK back in October 2013: "We've been fortunate enough to play every other festival on this planet numerous times, so Glastonbury is the only one that's eluding us.
Metallica - Master Of Puppets
"There's such a vibe and it's maybe the most quintessentially English festival."
He added: "Everybody who goes there loves it and obviously Michael (Eavis) doesn't need our help – I completely appreciate and respect that – but if he ever wants to get hold of us we're in the Yellow Pages and ready to go!"