We know Keira Knightley is British and all, but since when did she start dressing like a medieval knight?

We're only kidding -- sort of. The "Seeking A Friend For The End Of The World" star brought her charming accent over to "Late Night With Jimmy Fallon" to chat about soccer ("football," if you will), her new movie and that uber sexy Interview cover.

Knightley, of course, was utterly self-effacing when Fallon showed off the dramatic Interview shoot -- "It's Photoshop," she joked. But that 3-D dress, with strips of silver beading covering sheer black sleeves, was as real as they come, straight off the Valentino Fall 2012 runway.

Our first thought upon seeing Keira: coat of armor. But after watching her charm Jimmy's pants off in all her glittery-ness, we're liking the dress more and more. Plus all that sparkle matches her brand-new engagement ring, which explains the glow on her face.

Check out Keira's outfit below. Are you a fan of the extra-sparkly Valentino frock?

PHOTOS:

keira knightley late night with jimmy fallon

keira knightley late night with jimmy fallon

keira knightley late night with jimmy fallon

See Keira's style evolution!

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  • Behind the Scenes of Keira Knightley's Cover Shoot

    Having been voted one of the world's hottest, most fashionable young actresses, one would guess that Keira Knightley's wardrobe staple would be something lavish, perhaps designer shoes or a couture gown? No. The 27 year old reveals in the forthcoming issue of Marie Claire that her go to outfit is something rather more basic.

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