The 'Enter Sandman' hitmakers are set to be announced as topping the bill at Worthy Farm, Somerset, South West England on the second night of the iconic music event this June, The Sun newspaper reports.
Although many have expressed surprise at the decision to have a heavy metal act headline the festival, revellers don't think it matters too much who is chosen to perform on the main stage as the event offers so much choice.
Festivalgoer Philip Dore of Cardiff, Wales, said: ''I'm sure there'll be the usual whinging about how they're 'not a Glastonbury act', just like when Jay-Z headlined [in 2008].
''You know what? Never mind the haters. If people don't like Metallica, there's plenty of other acts on other stages. Who on earth is going to say, 'Oh no, I'm at Glasto on Saturday night, and I don't like Metallica! I wish I'd brought a book?' ''
And Pete Fellows, of London, added: ''I find it bizarre that people complain about the Pyramid headliners, there are dozens of other stages.''
Organiser Michael Eavis recently teased the Saturday headliner will be ''one of the biggest selling bands'' in the world.
He said: ''We are expecting to announce the full line-up at the beginning of May and everything is now in place. We are more than happy with the calibre of the acts and the headliner on Saturday will be one of the biggest-selling bands in the world at the moment.''
Meanwhile, the dairy farmer also revealed extensive work has gone into improving the much-maligned toilet facilities at the festival.
He told the Bristol Post newspaper: ''The toilets are really important for people and we work really hard to get them right. I have come up with a new design which we are calling the long drop mark three. We tried them out last year and they seemed to work well so we are increasing the number of them.''
Glastonbury 2014 takes place between 27 and 29 June. Tickets for the event have already sold out.
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