Robert Downey poses during a photocall for the film "Sherlock Holmes"

British actors Kelly Reilly (L) and Mark Strong (R) pose with U.S. actors Robert Downey Jr. (2nd L) and Rachel McAdams during a photocall for the film "Sherlock Holmes" in central London October 1, 2008.

Downey Jr. is to play Victorian super sleuth Sherlock Holmes in an upcoming blockbuster that studio Warner Bros, also behind the hit Harry Potter series, hopes will become a lucrative 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 in global ticket sales this year, and he promised his Holmes would be the best screen portrayal ever.

U.S. actors Robert Downey Jr. and Rachel McAdams attend a photocall for the film "Sherlock Holmes" in central London October 1, 2008.

British director Guy Ritchie (L) and U.S. actor Robert Downey Jr. attend a photocall for his film "Sherlock Holmes" in central London October 1, 2008.

U.S. actor Robert Downey Jr. attends a photocall for the film "Sherlock Holmes" in central London October 1, 2008.