The leading man also chats about his incredible birthday post for the singer!
ET sat down with the 'Rocketman' star ahead of the film's May 31 release.
ET was exclusively behind the scenes in London ahead of the Elton John biopic's release.
The new full trailer teases an intimate look at the beloved crooner.
'Rocketman' follows the transformation from shy piano prodigy Reginald Dwight into international superstar Elton John, out May 31.
The 'Game of Thrones' alum also talks to ET about those James Bond rumors and relives the moment his name was called.