Actress Keira Knightley only packed one week's clothing to film THE PIRATES OF THE CARIBBEAN because she was convinced producers would sack her when they discovered her amateur acting skills.

Knightley, who played ELIZABETH SWANN in the 2003 movie at the tender age of 18, was so scared she would fail to impress co-stars Johnny Depp and Orlando Bloom, she prepared herself for the worst.

But she insists her confidence is growing with every film she stars in and soon she will be proud to call herself an actress.

She says, "I don't even call myself an actress yet. I just don't think my skill level is that high, although I hope it gets better with every job.

"With Pirates (of the Caribbean), I only packed for a week because I was sure I was going to get sacked. I thought they'd made the hugest mistake."