Robert Downey Jr is to play the world's most famous detective in a new Sherlock Holmes drama.

The Iron Man star has signed up to take the lead role in Guy Ritchie's upcoming film based on the Arthur Conan Doyle creation.

And the announcement of Downey Jr's casting follows last week's news that Sacha Baron Cohen has signed up to play Holmes in a new spoof film, with Will Ferrell to play Dr Watson.

Ritchie was contracted by Warner Bros Studios in June to helm a film based on an as-yet-unpublished graphic novel take on the detective.

Former Warner Bros creative executive Lionel Wigram penned the comic and will also produce the film alongside Dan Lin, Joel Silver and Downey Jr's wife Susan Downey.

Though the plot of Wigram's approach to the 19th century detective remains a secret, it is believed it reimagines Holmes as a more adventurous character, who exploits his pugilistic talents and swordsmanship, according to Variety.

Warner Bros has been considering a new cinematic approach to the Baker Street resident for a number of years, with The Descent director Neil Marshall at one point attached to direct.

It was also confirmed last week that Columbia Pictures have a rival film in the works, a comedy starring Baron Cohen and Ferrell.

"Just the idea of Sacha and Will as Sherlock Holmes and Watson makes us laugh," said Columbia Pictures co-president Matt Tolmach in a statement.

"Sacha and Will are two of the funniest and most talented guys on the planet, and having them take on these two iconic characters is frankly hilarious."

10/07/2008 08:44:28