And hours after their unsettlingly sensual duet, the stars of A Star Is Born put on an even more shocking display of intimacy at the ultra-exclusive Warner Bros Pictures Oscars after-party.
In sensational photos exclusively obtained by Daily Mail, Gaga - born Stefani Joanne Angelina Germanotta - and Cooper are seen looking tactile as they chatted and embraced one another, despite Bradley's longterm model girlfriend Irina Shayk sitting just inches away.
Bradley and Irina are parents to their almost two-year-old daughter Lea De Seine.
According to a Daily Mail source who attended the elite gathering, after scooping the Oscar for Best Song Lady Gaga arrived at the bash and "made a beeline for Bradley" who was already there with Russian catwalk queen Irina and his mother Gloria.
The insider revealed the co-stars hugged repeatedly and spoke into each other's ear, adding "they were all over each other - they couldn't get enough of each other".
Gaga reportedly chatted with Cooper for almost two hours while Irina watched from the sidelines, looking unimpressed as she snacked on appetisers.
For the exclusive pictures, click here.
Earlier in the evening Bradley walked the Oscars red carpet with his mother and Shayk and seemed decidedly smitten with the mother of his child, squeezing her hand tightly and gazing affectionately at the 33-year-old Russian supermodel.
Irina was the first to stand to applaud the duo after their rendition of Shallow, and was seated in between Cooper and Gaga for the duration of the Awards ceremony.
The Sports Illustrated star was also photographed giving Gaga a warm hug after her Oscar win and her face seemed to show genuine pride.
