Jennifer Aniston has called her new movie Cake her biggest film challenge so far.
The movie is creating awards buzz, after it was met with a standing ovation at this year's Toronto International Film Festival.
Jen plays Claire, a woman coping with chronic pain who initiates a dubious relationship with a widower while concocting hallucinations of his dead wife.
Ahead of filming, the actress stopped working out so she could gain a few pounds, and in the film she sports a make-up-free face and unwashed hair.
The actress said the film was "a world away" from her new comedy, Horrible Bosses 2, in which she plays nymphomaniac Dr Julia Harris.
"It was such an extraordinary experience and the hardest thing I'd ever done creatively thus far, but on a personal and creative level, it was so important to me," she said.
"I have been dying to do something like that for a long time."
Asked about the potential for landing a big award for the role, she replied: "That would be so lovely. But I honestly don't think of it in terms of accolades."
:: Horrible Bosses 2 is in cinemas now.