James Corden red-faced over Keira Knightley joke

British funnyman James Corden was left squirming on the set of his new movie Begin Again over a gag he made years earlier about his co-star Keira Knightley.

The actor joked he had been sleeping with the Pirates of the Caribbean star during a speech at an awards ceremony in 2008, but he admits he now regrets the remark.

However, the gag came back to haunt him when he was cast alongside Knightley in the new comedy, and he suffered an awkward few days on set hoping she had forgotten about the comment.

Corden says, "That was quite a dark time in my life... It was awkward... (When we met on set) I didn't know whether to bring it up."