The Enter Sandman hitmakers were confirmed as Saturday night bill-toppers at this year's event following months of speculation suggesting Prince would make an appearance.
The announcement sparked fears the heavy rockers would be an awful fit for the festival, but Kasabian, who are headlining on the following night, are adamant Lars Ulrich and his bandmates will put on a great show.
Guitarist Serge Pizzorno tells MTV, "These boys, they're clever, man. They've been doing it a long time and there's a reason why they are who they are. I'm sure they'll pull something out the bag."
Singer Tom Meighan adds, "It's quite a bold move, Metallica - it's a monster."
And the Kasabian stars are quick to remind critics that they were convinced Jay Z wouldn't work as a Glastonbury attraction when he became the first rap act to headline the festival in 2008.
Pizzorno adds, "The thing is no one's really sure and usually that means something quite amazing will happen. Everyone was panicked about Jay Z... but look what happened."
Jay Z's set was hailed as one of the event's most iconic headlining moments.