VIDEO: Bradley Cooper Makes Surprise Appearance at Lady Gaga's Show - Watch Them Sing 'Shallow' From A STAR IS BORN

According to The Hollywood Reporter, Lady Gaga brought out special surprise guest Bradley Cooper at her show in Las Vegas last night. The pair sang the hit song 'Shallow' from the film in which they co-starred, A Star is Born.

Watch the full performance below!

Read more on The Hollywood Reporter.

In this new take on the tragic love story, Bradley Cooper plays seasoned musician Jackson Maine, who discovers-and falls in love with-struggling artist Ally (Gaga). She has just about given up on her dream to make it big as a singer... until Jack coaxes her into the spotlight. But even as Ally's career takes off, the personal side of their relationship is breaking down, as Jack fights an ongoing battle with his own internal demons.

The cast of "A Star is Born" also includes Andrew Dice Clay, with Dave Chappelleand Sam Elliott.

In addition to playing Ally, Gaga, who earned her Oscar nod for the song "Til It Happens to You" from "The Hunting Ground," performs original songs in the film, which she wrote with Cooper and a handful of artists, including Lukas Nelson, Jason Isbell and Mark Ronson. All the music is original and was recorded live.

"A Star is Born" is produced by Bill Gerber, Jon Peters, Bradley Cooper, Todd Phillipsand Lynette Howell Taylor. Ravi Mehta, Basil Iwanyk, Niija Kuykendall, Sue Kroll, Michael Rapino and Heather Parry serve as executive producers. The screenplay is by Eric Roth and Bradley Cooper & Will Fetters.

Collaborating with Cooper behind the scenes are Oscar-nominated director of photography Matthew Libatique ("BLACK SWAN"), production designer Karen Murphy, three-time Oscar-nominated editor Jay Cassidy ("American Hustle," "Silver Linings Playbook," "Into the Wild"), and costume designer Erin Benach.