Billie Eilish and Rosalía have shared their long-awaited collaboration, 'Lo Vas a Olvidar'.

The track was first discussed by Rosalía in 2019, when she said that she "couldn't wait" to finish the track. Eilish has been teasing the track all week on her Instagram, saying “You guys have been waiting for this.” Yesterday, she shared the video to her YouTube channel.

The video was directed by Nabil, who has worked with Kendrick Lamar, Dua Lipa, Vince Staples and SZA, among others.

The song will feature on an upcoming episode of HBO's hit show Euphoria, for which star Zendaya won her first Emmy award last year.

Eilish said that she reached “some notes I have never even thought about,” speaking to Annie Mac about recording her vocals for the song. She also sung Rosalía's praises, saying: “[Rosalía] knows what she wants, it’s very refreshing… I was like, ‘Wow, you’re the only person I’ve met who’s really like this’. It was dope to work with her. [She’s] the nicest girl, oh my god.”

Speaking to Zane Lowe, Eilish said that her whole family helped write the final line of the track. “So my Mom, my Dad, Finneas, me, Finneas’ girlfriend Claudia,” she said, “we all came down to the studio, and we listened, and me and Finneas were like, ‘Should we just write this line right now?'”

“I was sitting in the room with my entire family,” she continued. “We both, all of us, including my dad and my mom, they were like, ‘What if it was like….’ We were all giving ideas. So technically they should have a writing credit, because we all wrote that line right at the end.”

Eilish is currently working on her follow-up to her stellar debut album When We All Fall Asleep, Where Do We Go? and Rosalía is also working on her third album, following up 2018's EL MAL QUERER. '

Listen to the song below.