Robert Downey Jr was reportedly knocked out on the set of the new Sherlock Holmes film.

The 43-year-old actor was filming a fight scene for Guy Ritchie's new flick with 7ft tall co-star Robert Maillet when the wrestler threw a punch that left Downey Jr "out cold".

It is believed he had to have six stitches in his mouth.

Ritchie is directing the feature, a reimagining of Sir Arthur Conan Doyle's super sleuth, which began shooting in October.

The film also features Rachel McAdams as Irene Adler, the British sleuth's love interest.

Jude Law plays Sherlock's sidekick Dr John Watson.

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