The 44-year-old blonde actress portrays the royal, who died in a Paris car crash in August 1997, in forthcoming movie 'Diana' and she says it was important she told her story in a truthful way, reported Showbiz spy.
"It's very difficult to play someone who had such a deep impact and left such a lasting memory on the public. Our memory of her is still very fresh and you have to be respectful of that. It's also more complicated and sensitive when you take into account her two sons.
But I want to do her justice and tell her story truthfully," she said. Although Watts is expecting to get criticised for her portrayal of the much-loved princess, she says it was a role she could not turn down.
"There's a side that's terrified that my portrayal might not please the public which still has such vivid memories of her. But it's the kind of challenge I felt I couldn't refuse. You know that people will complain that you don't look enough like her, that you're not tall enough, all those things."