"There was a lot of pressure on me as the vehicle of his vision.He said to me, 'Just take it day by day, scene by scene.Originally Lars didn't want to cast me so the fact I look like her mother Jane Birkin was not the reason why I got the part.
She lived in Japan from the age of seven to 13 with her dad, Rene, a hair stylist and her mum Annette – then she returned to Paris until she moved to London aged 18 hoping to make it as an actress.
Von Trier and Martin talked a lot about what she could bring to the table as far as the character was concerned.
"We were clear this film wasn't about nakedness, but that it was part of the story. Lars wanted to celebrate the female desire and show we have flaws, we are human beings and not perfect," she says.
Martin, who is "itching" for her next role, joined an A-list cast including Uma Thurman, who plays one of her lover's wives, Christian Slater who plays her father, and Swedish actor Stellan Skarsgard, as an older bachelor, who listens to the nymphomaniac's life story told through Gainsbourg."In one scene I wear disgusting tight red high-waisted spandex pants which were absolutely vile with a zip and slutty tights and a tiny top like a handkerchief for a night out on the pull," she says in horror.
"I looked in the mirror and kept telling myself, 'You can do this'. There is a lot of humour which I hope people will understand.