Charli XCX thinks Katy Perry's gigs are "mental".
The 22-year-old pop star, who recently opened for the 'Roar' hitmaker as part of her Prismatic World Tour, has revealed her admiration for Katy and, in particular, her over-the-top stage shows.
She told Teen Vogue magazine: "I felt comfortable and at home, which was really nice. I've never opened for a superpop-tastic artist before.
"It's amazing to see the props and the amount of production she had. She's in the air, then on a horse, and then she's dancing, and the whole thing is mental."
Meanwhile, Charli revealed recently she's a huge fan of Justin Bieber and would love to write for the Canadian singer.
She said: "I like Justin Bieber as a pop star. I think he's really, really great. I really love the song 'Baby'. I think it's awesome.
"I would love to. I've never written for a boy before. I don't even know what I would say, but who knows?"
What's more, Charli said she's determined to focus her energies on songwriting following a period of writer's block.
She admitted: "[In April] I had a bit of a breakdown because I was feeling like I couldn't be creative enough so I've booked a load of studio time and I'm gonna be writing for myself, for my new project, and some other artists too. I can't say who. But yeah, there's songwriting going on right now."
She admitted: "[In April] I had a bit of a breakdown because I was feeling like I couldn't be creative enough so I've booked a load of studio time and I'm gonna be writing for myself, for my new project, and some other artists too. I can't say who. But yeah, there's songwriting going on right now."