Naomi Watts Credit: Splash News

Royal double take!

Naomi Watts is set to play the late Princess Diana in Caught in Flight -- and the Australian actress, 43, utterly transformed into the beloved royal shooting the biopic in London last week.

In a black pantsuit, with her blond hair in the wavy, short style of Prince William and Harry's famous mother, the blue-eyed Oscar nominee (who has two boys with her beau Liev Schreiber) was a convincing doppelganger for Diana, who died at age 36 in a tragic August 1997 car crash.

Directed by Oliver Hirschbiegel and written by Stephen Jeffreys, Caught in Flight will focus on the last two years in the life of Princess Diana; after famously divorcing Prince Charles, Diana reinvented herself as a global humanitarian and was on the path to self-fulfillment before she died.

"It is such an honor to be able to play this iconic role," Watts said in a February 2012 statement. "Princess Diana was loved across the world and I look forward to rising to the challenge of playing her on screen."

Jessica Chastain was first attached to the role last November in the film, which also focuses on Diana's relationship with Dr. Hasnat Khan, said to be the love of her life. Diana and Dr. Khan were together for two years before splitting in 1997; she rebounded by billionaire Dodi Al-Fayed, who died with her in the Paris car crash.

Tell Us: Does Naomi make a good Diana?