A day after his latest "Rambo" movie, "Rambo: Last Blood", debuted in third place at the U.S. box office with an impressive $19 million (£15.2 million) opening, the 73-year-old has confirmed his next project, about a young boy determined to find out whether a "mythical superhero" is alive.
Director Julius Avery raved about his casting coup in a statement to Deadline, writing: "Sly is a hero of mine (and) I'm incredibly thrilled to be working with such an iconic actor on this very special project."
Stallone's role in the project has not yet been announced, but reports suggest he'll portray missing-feared-dead superhero.
The film will be the first release for Balboa Productions, the company Stallone launched with business partner Braden Aftergood.
Meanwhile, not everyone is raving about Stallone's latest "Rambo" film - author David Morrell, who created the Vietnam veteran-turned-mercenary character in his 1972 novel "First Blood", has called the movie "a mess".
"I agree with these RAMBO: LAST BLOOD reviews," he writes on Twitter. "The film is a mess. Embarrassed to have my name associated with it."
"I felt degraded and dehumanized after I left the theater. Instead of being soulful, this new movie lacks one. I felt I was less a human being for having seen it, and today that's an unfortunate message," David told Newsweek.