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From the instant it was announced, the world's eye has been trained on the upcoming big screen Princess Diana biopic where Oscar-nominee Naomi Watts will play The People's Princess.

PHOTO - Naomi Rocks an Iconic Diana Dress

Now, with filming recently wrapped on 2013's Diana, the star is opening up to Manhattan magazine about this risky new role.

"Playing Princess Diana was the hardest thing I've done," Watts tells Manhattan magazine's editor-in-chief Cristina Greeven Cuomo. "I wanted to try to embody her and get the essence of her."

Watts goes on to say that the film "concentrates on [Diana's] love affair with a Pakistani heart surgeon," a story she admits to have been completely ignorant about prior to reading the script. And like much of the late Diana's life, Watts admits, "That love story ended sadly."

For more from Naomi Watts' Manhattan magazine interview, click here.