Lady GaGa has gushed about her ''true friend'' and ''artistic genius'' Bradley Cooper.

The 'Poker Face' hitmaker is still feeling the ''joy'' after her intimate performance of 'Shallow' with her 'A Star Is Born' co-star - which picked up the Academy Award for Best Original Song - and admitted that there is ''nothing more special'' than singing with the 44-year-old actor.

She tweeted: ''Nothing could be more special than sharing this moment at the Oscars with a true friend and artistic genius.''

The 32-year-old singer-and-actress also revealed that Bradley advised her to make sure she felt the ''joy'' during their magical performance.

Speaking to E! News, she said: ''What I would like to say is one of the hardest things in life is to be brave enough to be yourself.

''I wish to everyone that is going to that celebration to feel a joy inside of them.

''That's actually what Bradley said to me yesterday right before we did our last rehearsal for this performance of 'Shallow.' He said, 'Let's just drop a little bit of joy.'''

The 'Million Reasons' hitmaker added that the pair aim to ''spread love'' when they duet together.

She said: ''That's all that you can hope for. You can only pray that blessing of what you made can reach into the world and spread love.

''Of all things that we can spread, that's the most beautiful that we possibly could.''

Bradley's girlfriend Irina Shayk was in the audience watching as the pair performed cheek-to-cheek, but she was the first to get up on her feet for their standing ovation.

Gaga thanked her co-star and the movie's director during her acceptance speech, insisting there was ''not a single person on the planet'' other than Bradley she could have duetted with on the hit song from the movie.

She said: ''My family is here, I love you, mum and dad. Bradley, there is not a single person on the planet that could've sung this song with me but you. Thank you for believing in us, thank you so much.''