Wedding Crashers star Isla Fisher has revealed that she felt "vulnerable" in her latest voice role in Rise Of The Guardians.
The 36-year-old actress opened a "winter wonderland" inspired by the festive theme of the animated film in London's Leicester Square with co-star Chris Pine.
She braved the cold at the film's UK premiere in a white lace dress by Dolce & Gabbana and Sergio Rossi heels.
Despite having done voice work before in Rango and Horton Hears A Who!, the actress - who voices the Tooth Fairy - admitted: "I specialise in silly, funny voices but, for this, director Peter Ramsey told me to be myself but with an American accent. I felt quite vulnerable."
Fisher, who has two daughters with her husband, British comic Sacha Baron Cohen, denied that she picked the role for her children.
"My kids are too young to see this movie," she said.
"I think it's always important to choose stories and characters that you love. I felt that way and I'm really honoured to be a part of this," she added.
Pine, who is best known for playing Captain James Kirk in JJ Abrams' Star Trek reboot, admitted that lending his voice to Jack Frost was tougher than it seemed.
"It was very difficult. It's hard when you have to go to a booth all by yourself and figure out how it works. I have such a profound respect for these people now," said the 32-year-old.
Jude Law, Alec Baldwin and Hugh Jackman also lent their voices to Rise Of The Guardians, which opens in cinemas on November 30.