Bradley Cooper reveals what it was like singing on stage in 'A Star Is Born': 'I was terrified'

PHOTO: Bradley Cooper, left, and Lady Gaga in a scene from "A Star is Born."PlayClay Enos/Warner Bros. Pictures
WATCH Sam Elliott on why Bradley Cooper's voice convinced him to do 'A Star Is Born'

Bradley Cooper is gearing up for the release of his highly-anticipated film, "A Star Is Born."

Cooper and his movie co-star, Sam Elliott, stopped by "Good Morning America" Wednesday and Cooper revealed what it was like singing on screen in front of a crowd at the Stagecoach Spotlight Tour.

"Willie Nelson let us go on before him," Cooper recalled. "We just hopped on the stage and I said, 'Hi everybody, we're going to shoot a movie. It's all about you. Thank you.'"

PHOTO: Bradley Cooper, from left, Lady Gaga and Sam Elliott in a scene from A Star is Born. Clay Enos/Warner Bros. Pictures
Bradley Cooper, from left, Lady Gaga and Sam Elliott in a scene from "A Star is Born."
PHOTO: Lady Gaga, left, and Bradley Cooper in a scene from A Star is Born. Clay Enos/Warner Bros. Pictures
Lady Gaga, left, and Bradley Cooper in a scene from "A Star is Born."

He continued, "I was terrified. We were all terrified, the whole crew. No one had really ever done that before."

In the film, Cooper takes on the role of Jackson Maine, a singer-songwriter and Lady Gaga's love interest. Elliott plays the older brother and manager of Cooper's character. Elliott said he and Cooper broke the ice during their first meeting.

PHOTO: Bradley Cooper, left, and Lady Gaga in a scene from A Star is Born. Clay Enos/Warner Bros. Pictures
Bradley Cooper, left, and Lady Gaga in a scene from "A Star is Born."

"We finally got together and one of the first things he did, he played a tape for me of him working with a voice coach that he'd been doing for a number of months," Elliott recalled. "He said, 'This is going to sound a little weird' and it did sound a little weird because it sounded very much like me."

PHOTO: Bradley Cooper, left, and Lady Gaga in a scene from A Star is Born. Clay Enos/Warner Bros. Pictures
Bradley Cooper, left, and Lady Gaga in a scene from "A Star is Born."

Elliott also gave props to Cooper, who not only co-wrote the screenplay, but had his directorial debut.

"Bradley set a tone that allowed all of us to trust him," Elliott said. "I think when you can trust the director and trust your fellow actors, the odds are you're going to get to the truth and I think that's why this film is so special."

PHOTO: Anthony Ramos, Sam Elliott, Bradley Cooper, Lady Gaga, Dave Chappelle, and Lukas Nelson attend the A Star Is Born premiere during 2018 Toronto International Film Festival at Roy Thomson Hall Sept. 9, 2018, in Toronto. Kevin Mazur/Getty Images
Anthony Ramos, Sam Elliott, Bradley Cooper, Lady Gaga, Dave Chappelle, and Lukas Nelson attend the "A Star Is Born" premiere during 2018 Toronto International Film Festival at Roy Thomson Hall Sept. 9, 2018, in Toronto.

Cooper said it was other film directors who inspired him along the way.

"I think just being a student and having people like David O. Russell and Clint Eastwood be so open about their process and it's all rhythm too," he said. "A love story, it should breathe because you have to see them fall in love."

PHOTO: Bradley Cooper and Sam Elliott appear on Good Morning America, Oct. 3, 2018. ABC News
Bradley Cooper and Sam Elliott appear on "Good Morning America," Oct. 3, 2018.

"A Star Is Born" hits theaters this Friday.