WATCH: Lady Gaga & Bradley Cooper Bring the House Down

Lady Gaga surprised her audience in Vegas w/ a special guest...

During Lady Gaga’s Las Vegas concert over the weekend a true to life movie moment occurred when the world’s most popular not-actually together couple reunited to perform “Shallow,” from “A Star is Born.”

Currently nominated for “Song of the Year” at the Grammy Awards February 10th, Bradley Cooper’s obviously a great actor but Gaga owns any stage she walks on.