Natalie Portman's biggest fear is tripping up on the red carpet.

The Oscar-winning actress might look calm and collected during high profile events, but she confessed she secretly panics about landing flat on her face in front of the world's media.

She told France's Madame Figaro magazine: ''It's a very serious game. I remember my first red carpets, I felt like I was wearing a costume, it was hilarious. Nowadays, I'm used to it: you just need to look happy even if you're wearing uncomfortable shoes or a dress you regret having chosen.

''My top tip? Looking confident and calm. My biggest fear? Tripping up. When I was pregnant, it was an obsession, I kept repeating to myself, 'Don't fall, don't fall.' ''

After a successful campaign for Miss Dior Cherie fragrance, the striking star has become the new face of Rouge Dior lipstick and says advertising a red lipstick was an obvious choice for her.

Asked what the colour red means to her, Natalie, 32, mused: ''Passion, of course. Confidence, strength, seduction, femininity. It's the colour of brunettes. When I put red lipstick on, it's because I want to be admired... by my husband.''