Austin Butler was hospitalised immediately after filming 'Elvis'

He said: "It was all-consuming. Then my body just said, 'All right, I need to rest' [and I went to the hospital]."

The 'Once Upon a Time in Hollywood' star - who lost his mother Lori to cancer back in 2014 - then went on to reveal that he felt a "connection" with Elvis Presley because he had also lost his mother Gladys to the disease back in 1958.

He told EW: "That was one of the first keys that connected me to him on a very human level rather than the idea of Elvis. Learning how close he was with his mom, because my mom was my best friend, I could connect to him on that level of grief."

Austin then explained that since completing the movie, he feels as if the 'Hound Dog' hitmaker - who died of heart disease at the age of 42 back in 1977 - is now a "close friend" to him and spoke of how he wanted to make Elvis's former wife Priscilla "proud" with his performance.

He said: "Elvis now this really close friend that I can come back to, and I always get joy in his presence. I'll pop on his music or watch one of his films. It'll always be a close part of my life. I wanted to make Priscilla proud and do justice to her and her family."