Kristen Stewart admits she didn't read the script before taking her Princess Diana role

• Stewart admits she agreed to play Princess Diana in "Spencer" by only talking to the film's director.
• "Kind of without thinking, very irresponsibly, I said 'Yes, absolutely,'" she said.
• "Spencer" follows Princess Diana in the days leading up to her divorce of Prince Charles.

Most actors want to get their hands on the script before agreeing to a role, but Kristen Stewart admitted that for one of her most challenging roles to date, playing Princess Diana in the upcoming movie "Spencer," it didn't happen like that.

All she needed was a talk with the movie's director Pablo Larraín.

"He called me on the phone," Stewart said during a conversation at the Toronto International Film Festival, according to IndieWire. "At first I hadn't read the script yet and he proposed this idea and said he was doing this sort of weird tone poem about Diana, and asked whether or not I would be interested in tackling the subject at all - before he sent the script."

"Kind of without thinking, very irresponsibly, I said 'Yes, absolutely,'" Stewart recalled. "I could have totally fucked it up."

But Larraín has a great track record in profiling famous women in a unique way. He oversaw Natalie Portman's transformation into Jackie Kennedy for the 2016 movie "Jackie." Centered on the former first lady in the days following the assassination of her husband, John F. Kennedy, the performance led to Portman earning a best actress Oscar nomination.

So talking to Larraín was all Stewart needed to portray Princess Di in a movie that focuses on the tumultuous days leading up to her splitting from Prince Charles.

Spencer also revealed that she didn't feel much pressure playing the role that will certainly be analyzed by many all over the world.

"I knew there was no way to play this part perfectly and therefore it was easier," she said. "Or at least easier to not be so intimidated and so daunted."

"I could only be my version of that and kind of hope that if I learned everything about her, and absorbed her, and kind of meld, and be both me and her in some sort of weird way, it was going to be the best version," she added.

But Stewart admitted she did want to make sure she got one thing right: how Princess Diana was as a mother.

"I think that her strength and her power and her feral, unstoppable force of nature really, really comes out when she was with her kids," Stewart said. "She wasn't very good at protecting herself, but she was really good at protecting them."

"If you don't get that right, you don't get her right," she added.

"Spencer" will open in theaters on November 5.