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Actress Keira Knightley deliberately dresses down when she is out in public because, she says, she's too shy to talk to her fans.

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The "Pirates of the Caribbean" star admits she struggles with fame because she is naturally "very shy" and feels uncomfortable when members of the public stop her in the street.

Knightley always wears her scruffiest clothes when out and about in a bid to go unnoticed, and avoids showbiz parties to maintain her low profile, but the 25-year-old fears her tactics aren't working.

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She tells Britain's Vogue magazine, "I think (fame) broke something in me. I was told very early on that if I didn't go out to openings and parties and events, I would be left alone. I didn't, and they still didn't leave me alone. I knew it was part of the deal in the life I had signed up to, but the fear of it has never left me. I'm still not good at being recognized. I wear scruffy clothes and hats and keep my head well down. I'm sure people must think I'm a complete b--, but I'm just very shy."

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And Knightley suspects she has riled gossip columnists over the years by failing to provide them with any scandal, adding, "I was so young when it started. I was involved in 'Pirates' from the age of 17 until 21. At that time people couldn't get enough of people falling out of nightclubs with their knickers showing, and I wasn't giving them that -- and I think it infuriated them."