Bradley Cooper surprises fans as he jumps on stage to perform with Lady Gaga in Las Vegas

Lady Gaga is scheduled to perform "Shallow" at the Oscars next month, but she got in a little early practice with her "A Star is Born" costar Saturday night.

Gaga brought Bradley Cooper on stage as a surprise during her Las Vegas show to raucous applause.

As he walked on stage with his backstage pass dangling from his neck, Gaga ran over and gave him a big hug before they moved over to her piano.

The two channeled Jack and Ally as they sang "Shallow," the film's title track, which is nominated for Best Original Song at the Academy Awards. The song won the Golden Globe earlier this month and is expected to win at the Oscars as well.

Before inviting him on stage Gaga told the audience, "You may have heard of that movie, 'A Star is Born.' ... Hey Bradley, wanna come up and do this one with me?"

Cooper, who also directed the film, sang along with Gaga and even rocked out with a little air guitar during the performance. Unsurprisingly, the footage hit social media seconds after the performance.

Cooper was snubbed in the Best Director category after being nominated in the Golden Globes. He wouldn't actually win an award for the song "Shallow" though, which was written by Lady Gaga, Mark Ronson, Anthony Rossomando and Andrew Wyatt.

But each has a chance to leave with a gold statue. Gaga is nominated for an Oscar in Best Actress in a Leading Role, while Cooper is up for Actor in a Leading Role.

Lady Gaga signed on for a residency at the Park Theater at MGM last year. She will perform 20 shows in 2019, with Saturday's show being her fourth. She has just one show in February, leaving plenty of time for her to get ready for the Oscars on Feb. 24.