If there's anything that gets us almost as excited as the release of "Breaking Dawn - Part 2," it's the arrival of its A-list-stacked soundtrack, which hits shelves Tuesday.

MTV News was lucky enough to premiere the video for Green Day's first-ever contribution to a "Twilight" soundtrack, and we recently sat down with admitted fan and repeat contributor Christina Perri to talk all about her revamped version of "A Thousand Years" in "Breaking Dawn - Part 2."

As it turns out, Perri — who penned "A Thousand Years" for "Breaking Dawn - Part 1" — was surprised to find out the studio and her record label wanted a new version of the song, especially because the singer had to pass on writing another original song for the soundtrack due to her busy tour schedule.

"I found out while on tour and got a phone call from the head of Atlantic Records, Craig Kallman, who never called me before. I thought I did something terrible," she recalled. "I was not expecting it."

Perri said Kallman called after seeing an early cut of "Breaking Dawn - Part 2," in which the editors had used "A Thousand Years" as a temporary track for one of the film's most moving and final scenes. Because it was a perfect fit for that moment, they asked Perri if they could use an extended version in the film, and she was immediately onboard.

" 'A Thousand Years - Part 2' is longer. In the film, it's about six minutes, but on the soundtrack, it's shorter," she explained. "I added a pre-verse, because they wanted something special and new, and I found adding a verse in the middle didn't make sense with the story. I wrote the [original] song from Bella's and Edward's perspective like a duet, and then we didn't have the time or the person when we first released it to make it a duet and it didn't make sense.

"In adding a pre-verse, the way the scene ends the whole series, it made sense to add it to the beginning," Perri continued. "I made it a duet with a guy named Steve Kazee, who is a super amazing Broadway star, Tony Award winner [for 'Once'] and an incredible human being."

Check out everything we've got on "The Twilight Saga: Breaking Dawn - Part 2."