Billie Eilish has revealed that she was quite the Justin Bieber fangirl as an adolescent.
And the Biebs has returned that sentiment, showing support for the young artist whenever he can.
He recently got emotional as he opened up in an upcoming interview about feeling protective over Eilish.
The 25-year-old told Apple Music’s Beats 1: '[I’ll] let her do her thing and if she ever needs me, I’m gonna be here for her. Just protecting those moments because people take for granted encounters.'
He's no stranger to early fame, as he received his breakout at age 13 after being discovered by Scooter Braun and Usher.
Bieber continued: 'I just wanna protect her, you know? I don’t want her to lose it.
'I don’t want her to go through anything I went through. I don’t wish that upon anybody. So if she ever needs me, I’m just a call away.'
Eilish, 18, posted the clip to her Instagram, accompanied by photos of her childhood bedroom adorned with posters of Bieber.
She also shared a throwback snap of herself sporting a sleeveless white t-shirt printed with his autograph.
The Bad Guy artist also promoted Bieber's first new album in five years, writing in the caption: 'stream changes.'
He released the new album on Valentine's Day, recently promoting it with a performance on Saturday Night Live.
During the interview, Bieber also revealed how wife Hailey Bieber inspired some of the new music.
He said: 'I mean, I want to continue to write about what it looks like to be… This is an album I wrote in the first year of our marriage, so it’s so fresh.
'There’s so much more to learn about commitment, and building trust and foundation. I’m looking forward to continuing to build and make music that’s going to reflect that. I think I’m excited about this, but I’m just like, there’s so much more.'
Eilish also released some new music this week, as she recorded the theme for the upcoming 007 film No Time to Die.
She's had quite the rise to fame, recently breaking records as the youngest artist to win the top four categories at the Grammy Awards.
Bieber released a remix of Eilish's breakout hit Bad Guy back in July, sharing the track with a photo of a young Eilish in her Bieber-themed room.
© Associated Newspapers Ltd.