Watch: Lady Gaga & Bradley Cooper Perform 'Shallow' Together for First Time

Bradley Cooper stopped by Lady Gaga's Las Vegas residency "Enigma" Saturday night to perform – for the first time live – their smash song "Shallow" from "A Star is Born."

The actor and director of the Oscar nominated film surprised little monsters when he unexpectedly showed up at Gaga's show.

"Shallow," written by Gaga, Andrew Wyatt, Anthony Rossomando and Mark Ronson, won a Golden Globe and it's also nominated for an Oscar. Gaga and Cooper are both nominated for Oscars in their respective acting lead acting categories and "A Star is Born" is up for Best Picture. Sam Elliot earned a nod for Best Supporting Actor and the film is also up for Best Adapted Screenplay, Best Cinematography and Best Sound Mixing.

Watch Gaga and Cooper perform "Shallow" below.