A day before the world's most photographed woman is reincarnated again in the world premiere of a Hollywood film, the actress who reinterprets her last two years for the silver screen is full of trepidation.
"Of course, I'm nervous. I'm nervous as I always am when we come to a point when the film is being viewed by the audience," Naomi Watts says.
She was speaking to the press in a hotel in London to promote Diana, which opens in Singapore tomorrow.
"In this case, it's much more nerve-racking because everybody walks in there knowing who she is."
In a little black number that accentuates the actress' bird-like features more than her curves, one would imagine conquering the red carpet to be little more than a matter of professional equanimity for the British-born, US-based artist, acclaimed for her roles in Mulholland Drive (2001), 21 Grams (2003) and The Impossible (2012).
After all, she has had to live through similar moments in real life as a celebrity, and on screen as the late Princess Diana, self-appointed "Queen of People's Hearts".
Watts, 45, admits that she took a while to agree to the role, conceptualised by screenwriter Stephen Jeffreys in a movie directed by Oliver Hirschbiegel (Downfall, 2004). Since its release in the United Kingdom in September, the film has been slammed by the British press for over-sentimentalism.
In an interview prior to its debut, Watts herself was all-a-jitter and defensive of her choice.
"I wrestled with the decision in the beginning. How do you take possession of a character that everyone feels they know so well?" she asks.
"But what made me say 'No' was also what made me say 'Yes' in the end. It also intrigued me, that challenge. Taking that kind of transformation physically was an interesting idea."
Indeed. For many audiences, one of the movie's most titillating draws would be measuring Watts up - and her make-up and fashion team - exactly against the much-filmed and written-about Diana.
No surprise, then, that the actress admits to becoming nothing short of "obsessive" about her target. She read every book, article and letter she could lay her hands on.
She had Diana's historic Panorama interview with Martin Bashir on her iPod on repeated play while running in the park and driving around town. She froze part of her face to capture the late princess' unique facial gestures and mannerisms.
On occasion, filming was surreal - not least when Watts had to wear Diana's clothes.
"The pale blue dress; that one by Azagury. According to the designer that was the actual dress that she wore," she says.
"It fit me. It was eerie. I was quite impressed and surprised by how short it was."