Robert Downey Jr. to play Sherlock Holmes

By Mike Collett-White

LONDON (Reuters) - Robert Downey Jr. is to play super sleuth Sherlock Holmes in an upcoming blockbuster that studio Warner Bros. hopes will become a lucrative new franchise.

The 43-year-old said one reason he was chosen for the role may have been his involvement in action movie "Iron Man," which earned over $570 million (322 million pounds) in global ticket sales this year, and he promised his Holmes would be the best screen portrayal ever.

"In case you aren't aware I had a hell of a summer, and it's made me much more viable to play a lead role than I might have (been) in the past," Downey Jr. told reporters in London, where shooting on "Sherlock Holmes" is about to begin.

When asked what he could bring to a character portrayed countless times on film and television, he joked: "Clearly I'm going to do it better than it's ever been done.

"The more I read about it the more overwhelmed I was by the weight of it and the amount of people who will be watching to see if it's gotten right."

As well as bringing more action sequences to the story, the dynamic between Holmes and loyal assistant Dr. Watson looks set to differ from what audiences are used to with the casting of heartthrob Jude Law in the part.

Director Guy Ritchie said "Sherlock Holmes" was his biggest movie "by a long shot" in terms of budget.

Producer Joel Silver would not name the figure, but he called the budget "healthy" and said plans had not been affected by recent turmoil on the financial markets.