Watch Lady Gaga, Bradley Cooper’s Steamy ‘Shallow’ at Oscars

Lady Gaga and Bradley set social media gaga Sunday with their steamy rendition of the song "Shallow" .

The "A Star Is Born" co-stars surprised the audience by taking the stage to perform the emotional ballad without an introduction.

They turned up the heat when Cooper joined Gaga on her piano bench, singing their last harmonies into one microphone together, and fans were all over it, declaring the pair stole the show.

Gaga and Cooper's  swoon-worthy chemistry made this the telecast's easy highlight, as the former co-stars sparked romance rumors on social media with their unusually close and googly-eyed performance.

Watch for yourself.  Here's video of Sunday night's live performance.