Lady Gaga, Bradley Cooper and Jennifer Esposito. Picture: Twitter/AP

The intense duet between Bradley Cooper and Lady Gaga at the Oscars on Sunday night won a standing ovation and sparked a flurry of comment on social media.

The "A Star Is Born" actor-director and co-star Lady Gaga, who split from her talent agent fiance Christian Carino only last week, performed their Academy Award-winning song, "Shallow" which ended with Cooper, 44, perched beside Gaga, 31, on the piano stool, with his arm around her waist and tilting his head toward hers as they gazed into each other’s eyes.

And it all happened while Cooper’s model girlfriend – and mother of his one-year-old daughter – Irina Shayk watched from the front row.

Actor and comedian David Spade also weighed in on the matter on Instagram. On Sunday night, Spade took a photo of their performance and asked his Instagram followers, "Is there any chance these 2 aren't f**king?"

Cooper's ex-wife, Jennifer Esposito, then commented on Spade's post by writing "ha".

E! Online reports that Esposito and Cooper were married for just four months and got divorced in 2007, and in 2014 she reportedly called out her ex in her book in which talks about her battle with Celiac Disease.

Esposito described Cooper as "funny, smart, cocky, arrogant, and a master manipulator with a cold, mean side".

Meanwhile, Gaga told E! News during an interview in January that her chemistry with Cooper is real and continues to grow.

"My chemistry with Bradley is real, you know? It was instant when we met, and it only continued to grow," she said.