In Ritchie's Warner Bros film, Robert Downey Jr plays the detective and Jude Law plays Watson.
However, in a second film, Ali G creator Sacha Baron Cohen also stars as the fictional detective alongside US actor Will Ferrell as the sleuth's crime-solving partner in the Hollywood film from Columbia Pictures.
Joel Silver, a co-producer of the Ritchie movie, said the film, which is based on a comic book featuring the detective as a skilled swordsman, would be out first.
He said of the rival film: "I heard about it when we were putting the final deals together.
"Ours is serious... theirs is a comedy. We're not going to be coming out together... I hope what we've done is launched a franchise."
Ritchie said his film, an "intelligent" action movie, would probably contain more fight scenes and violence than previous on-screen incarnations of the detective.
I was not told about this. Why was I not told about this? Was there a memo? Communiqué of some sort? I did not receive it.