LONDON — Poor Dr. Watson. Always the sidekick, never the star.

Jude Law hopes to rectify that situation with his charismatic performance alongside Robert Downey Jr. in “Sherlock Holmes,” making the detective’s right-hand-man a handsome action hero in his own right. He’s just not that comfortable with his new nickname: “Hotson.”

“Mostly I was only hot because I was wearing those thick tweed suits, massive overcoats, and hat and gloves,” Law said.

Law stresses that the film’s version of Watson — a dapper army veteran with an eye for the ladies — is firmly based on the 19th-century stories by Sir Arthur Conan Doyle. Director Guy Ritchie wanted to give the tales a 21st-century spin while staying close to the original material.

“There’s a reference in one of the books to Watson being very popular with women,” Law said. “So that fits.”