Bradley Cooper felt "comfortable" singing with Lady Gaga in 'A Star is Born'.
The 42-year-old actor - who directed the production and also portrays Jackson Maine in the remake of the 1937 film - performed live with the 'Bad Romance' hitmaker, who portrays Ally in the musical drama, at the Coachella and Glastonbury festivals while being filmed for the movie, but he was not fazed about belting out the ballads with the 31-year-old singer.
Speaking to Entertainment Weekly magazine about working with Gaga - whose real name is Stefani Germanotta - he said: "[She] made me feel comfortable."
And the 'Burnt' star never felt he was "nuts" for taking to the stage alongside the 'Joanne' singer for certain scenes in the film.
He added: "I never had to deal with the reality of asking myself, 'Are you nuts, putting yourself on stage with Lady Gaga?'"
But Bradley is not the only star who enjoyed working on the project, as Gaga loved working with the "dream team".
Alongside a post of her on set, which was previously shared on her Instagram account, she wrote: "That's a wrap on #AStarIsBorn Flowers for my directors and producers. absolutely a dream team (sic)."
Bradley has also sang his co-star's praises, as he has described her as an "incredible" artist.
Speaking previously, he said: "She's unbelievable. She really is incredible.
" I thought I sang. I was like, 'Yeah, I sing.' It's so hard to sing! Like, people cook - but then there's cooking. I'm a good cook, but to be an amazing chef...So, singing, I had no idea.
"I would get fatigued at the end of even a phrase...I've really been awakened to the phenomenon of singing.
"I just hope I can be believable enough so you can watch Stefani - that's her name, Gaga - just shine. Because she's incredible."