The actress earned acclaim for her performance in the film alongside Bradley Cooper and scooped the Oscar for Best Original Song for 'Shallow' at the 2019 Academy Awards.
"I didn't feel the pressure at all. I only work on things I believe in," explained Gaga of her role as Patrizia Reggiani in the biographical crime drama.
"I read the script and thought it really fascinating and interesting and then I met Ridley Scott and I was so excited to work with Adam (Driver, co-star)."
Al Pacino also appears in the movie and the "Stupid Love" hitmaker admitted the experience prompted a rollercoaster of emotions.
"It was terrifying, exciting, amazing, it's Al Pacino! He entirely transformed the landscape of acting in cinema and I have admired him for a long time," she said.
The role also required the singer-turned-actress to speak in an Italian accent - and she kept up the habit for "the whole of filming."
"I started on the voice six months before we started shooting and I stayed in it for the whole of filming, which I am sure was super annoying for Adam," Gaga laughed.
"For me I thought it was harder to go in and out, so I stayed in character."