Starring alongside Costner in The Bodyguard 2, would have been the Princess of Wales first acting role and would have been all thanks to Sarah Ferguson, Duchess of York.
"Sarah was really important. I always respect Sarah because she's the one that set up the conversation between me and Diana," Costner revealed.
"She was the one that set it up, and she never said, 'Well, what about me? I'm a princess, too.' She was just so supportive of the idea."
In an interview with Anderson Cooper back in 2012, the director told Cooper that he received the script for the film just one day before Diana's fatal car crash in Paris.
The Bodyguard was a box office smash hit in the '90s, with the original film starring the legendary Whitney Houston.