Billie Eilish "feels protective" over fellow pop star Olivia Rodrigo.

The 21-year-old 'Bad Guy' singer has admitted she "worried" about Olivia, 20, rising to fame as a child star in the acting industry before becoming a full-time singer and even wrote a song called 'Goldwing' about her.

Billie told the Los Angeles Times: "I think everybody’s experiences are so individual … Nobody has had anybody else’s life, you know? But I do feel a protectiveness over Olivia.

"Olivia was getting big, and she was just, like, this little dainty child. I felt so nervous. I was worried about her. She came up in that acting world, and people are so weird. I don’t know - I just felt very protective over her."

Billie went on to reveal Olivia - who rose to fame on kids TV show 'Bizaardvark' - was the inspiration for her track 'Goldwing' from her 2021 album 'Happier Than Ever' which features the lyrics: "They're gonna tell you what you wanna hear / Then they're gonna disappear / Gonna claim you like a souvenir / Just to sell you in a year."

The singer added to the newspaper: "It’s not only about her. I was just thinking about her when I was writing it. She was coming up, and she was younger than me, and nobody had ever been younger than me ... I feel that way to everyone. I just see myself in all these young girls."

Billie has been open about her own struggles with fame and previously admitted she feels full of "doom" because her life is now so public.

She told Allure magazine: "I’m starting to do better [at dealing with fame], but I’ve not been doing so great, to be honest. I have impending-doom feelings most of the day. When I think too much about it, how I can never have privacy again, it’s enough to make you want to do all sorts of crazy things. But you have to let it go."