The actress plays the late British icon in Oliver Hirschbiegel's upcoming movie Diana, which details the final years of the princess' life prior to her death in a car crash in Paris, France in 1997.
Watts has already wowed critics with her haunting resemblance to Diana in the film, and now she has revealed she was so convinced the royal was watching over her, she would consult her over each scene.
The actress tells British magazine Event, "There were definitely moments when I felt Diana's presence - I dreamed about her a lot, too, and that's a first. I kept wondering to myself: 'Would she have liked it?'
"So I found myself constantly asking for her permission to carry on. I had saturated myself with Diana and her life and I felt this enormous responsibility of playing this iconic woman. It felt like I was spending a lot of time with her. There was one particular moment when I felt her permission was granted. That won't sound right in print, I know."