A good line of dialogue can make a career. At just 19, Keira Knightley owns one widely quoted multiplex moment. In last summer's Pirates of the Caribbean: The Curse of the Black Pearl, Knightley dismissed a black-toothed marauder with a metal pole and the trailer-ready line, "You like pain? Try wearing a corset." Now, if all goes according to plan, she will add a second epigram to her name. In King Arthur, which hits theaters nationwide on July 7, she plays Guinevere as a heavily muscled, lethal woman warrior. (Arthur, like Pirates, is a Jerry Bruckheimer production.) When one of the more sensitive knights of the Round Table confesses before battle to fearing the hairy, scary enemy, Knightley's Guinevere scoffs, "Don't worry, I won't let them rape you."
With a bit of tweaking, both lines could have been delivered by Arnold Schwarzenegger, which may explain why Knightley has so quickly ingratiated herself with moviegoers--and also why she doesn't consider it much of an achievement. Knightley, a native Londoner, has a refined look, brisk comic timing and a brawler's instinct for knowing when to shut up and throw a punch, but that doesn't mean she's ready to tackle Chekhov. "I don't think I can call myself an actress yet," she says. "I just don't think my skill level is that high. I hope that with every job it gets better. But until I'm good, I can say I'm trying to be an actor, but I don't think I've completely made it."
Knightley isn't being modest. She just doesn't believe in kidding herself. Of the acting challenge presented by King Arthur, she says, "I had to work out physically quite a bit, but pretty much it's scream a lot and enjoy being painted blue." (Her Guinevere wears so much blue war paint that she looks like the world's most ferocious Smurf.) Knightley is similarly dismissive of her breakthrough role in Bend It Like Beckham and her beatific cameo in Love Actually. Few actresses talk as frankly about the artistic limits of their work or as exuberantly about their physical imperfections. (Knightley likes to point out her acne for those who can't see it.) Few actresses also refuse to hire a personal assistant on the grounds that it would feel "absurd" to do so. Yet all this self-deprecation may explain why she's a burgeoning star. "She really does lack pretense," says Bruckheimer. "I'm a big believer that if you project somebody on a 100-foot screen, you look into their soul. Keira appreciates everything she gets, and she doesn't take herself seriously. Believe me, the audience sees that. Honesty and believability make movie stars. She's got both."
By sunnily questioning her talent and not approaching each role with a cyborgian ambition to be the next Julia Roberts, Knightley has separated herself a bit from the ever expanding galaxy of post-adolescent It girls (see box)--and staked a slightly more credible claim to actually being the next Julia Roberts. Knightley has Roberts' angular frame, avenue-wide smile and unforced sass, and she's grateful for what she calls the "insane and ridiculous luck I've had getting these big roles," but she does not possess the genetic code to be happy as a full-time romantic heroine--pirate thwacker. (To date, she is a holdout from the Pirates sequel.) What she would rather do is "keep learning, do strange things, keep pushing to get better."