By Lynette Rice
Updated August 15, 2010 at 10:30 PM EDT

Image Credit: Karen BallardSylvester Stallone told the Hollywood Reporter that he’s already thinking about a sequel to The Expendables, which opened at No. 1 this weekend by grossing $35 million. “I believe this group has to continue to evolve – it just can’t become the same people,” he told the trade publication. “So how do you get new people introduced into the group, and how do you have some of the other people leaving? Those are the challenges.”

Stallone said one of the proudest moments of his career was completing the Rocky franchise with the 2006 sequel Rocky Balboa. “To be able to meet the challenge of completing that series after all these years, that was great. But this one here tops that — not in an emotional way but for excitement. This should have never happened. (Producer) Avi Lerner really took a big gamble on me with this when nobody else would. I know because I heard about it every day! He kept worrying about the reviews.”