Keira Knightley once posed for a picture with a fan - who thought she was Britney Spears.

Keira Knightley

Keira Knightley

The 33-year-old actress admitted it was a very "weird" case of mistaken identity but she "quite enjoyed" being recognised as someone completely different.

She told 'Late Late Show' host James Corden: "In LA, I was in a shop... it was a weird one... I had my picture as Britney Spears, as well.

"I quite enjoy it. I'm much more polite, I think, when people think I'm somebody else."

James quipped: "I would love to see that person with their friends."

But Britney isn't the only famous person Keira has been mistaken for, though she can understand some of the other comparisons.

She explained: "I've been chased through an airport as Natalie Portman. I've been chased through a park as Kate Winslet.

"Quite a few people have come over to me to ask me to, 'Say hello to Daniel Craig' for them because they think I'm Rachel Weisz...

And... Britney Spears!

"The other ones I get it - English actresses - but [not] Britney Spears!"

Keira is particularly unsurprised to have been mistaken for Natalie Portman "a lot" as she was cast as the 'Black Swan' actress' decoy in 'Star Wars Episode I: The Phantom Menace' in 1999 in due to striking similarities.

She confirmed: "I have had many pictures as Natalie Portman."

While the 'Colette' actress doesn't mind being mistaken for someone else, James insisted he wouldn't be impressed if it happened to him.

He joked: "If anyone would ever think - not that they ever would - that I was someone else... I would be awful!

"If someone came up and said; 'Wow, Matt Damon's put on a few pounds! Will you sign this?' I would be like, 'Leave me alone, you ass hole!' "

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