Billie Eilish suffered "an intense amount of writer's block" when she tried to pen the 'No Time To Die' theme song.
The 19-year-old singer wrote the song with the help of her brother Finneas O'Connell, but she admits that it wasn't a straightforward process.
Billie said: "We had an intense amount of writer's block as soon as we were called to action."
Finneas added: "We rented out a studio to go and try to write it - and we didn't write anything good."
Billie and Finneas, 24, eventually ended up penning the song on a tour bus in Texas.
Billie explained: "Finneas came up with this piano motif and immediately we were like, 'Ohhhhhh', and we wrote the whole song."
Billie and Finneas had both dreamed of creating a Bond theme song long before they were offered the opportunity.
The 'Bad Guy' hitmaker told the BBC: "We'd always wanted to write a Bond song - even before it was an option."
And her sibling added: "We'd been writing motifs and thinking of melodies for a couple years, just as far as like, 'Wouldn't it be cool if one day we got to do a Bond song?' And when we got wind that they were making the 25th, we immediately set out to meet with Barbara [Broccoli, producer] and plead our case."
Meanwhile, Finneas previously admitted that they were "lucky" with the name of the new movie.
The acclaimed songwriter joked that other artists haven't been as fortunate in the past.
He said earlier this year: "We were lucky, because the title was 'No Time to Die', and that is a good lyric.
"I don’t fault Jack White and Alicia Keys for not writing a song called 'Quantum of Solace'."