Billie Eilish. [Source: TVNZ]

Billie Eilish fears she might bomb at Glastonbury if she overthinks her history-making slot.

The 20-year-old Grammy winner will become the festival’s youngest solo performer when she takes to the Pyramid Stage on Friday night as the event returns after a three-year hiatus due to the pandemic.

She told Matt Wilkinson’s ‘Glastonbury Special’ on Apple Music 1 on Tuesday “With this kind of thing, which is doing this kind of show and headlining and with all the pressure of it, it’s like, if you overthink it, you might bomb.

“So I try to keep myself as composed as possible. But if I do think about it, it’s like the coolest that I’ve ever heard. I mean, Glastonbury. Come on. It’s so cool. So I’m very, very geeked, very excited.”

The singer added she had no hesitation accepting the slot beyond checking if it fit her schedule.

She also said she now has an elaborate pre-stage ritual that involves two workouts after previously winging it ahead of gigs.

Eilish said: “I only this year even have had like a pre-show ritual because before I literally just goofed around until I went on stage. I didn’t even warm up.

“Now, I have two hours beforehand. I work out for a while and then I do my own.

“So I do my own makeup and then I do my own hair and I have to do it a very specific way. And then I have to find an outfit and then I have to make sure the outfit fits right. And then I have to put all of my fricking jewellery on which takes my three hours or whatever.

“And then I get my ankles taped. And I get my shins taped. And that takes a while. And then I warm up my voice. And then I do more hair. And then I do another warm-up. And then I go on stage.”