The Hollywood action man, who created and starred in the Rocky franchise, teamed up with champion boxing brothers Vladimir and Vitali Klitschko to bring his classic 1976 film to the stage.
He was in Hamburg over the weekend for the production's opening night, and is hoping the show will be a knock-out with audiences.
Stallone says, ""I'm so happy. It's amazing that the Klitschkos are here and they're giving birth to something that is first on the planet. I'm proud of you guys. I'm proud of Hamburg. Thank you!""
Vitali adds, ""Sylvester Stallone is the Pope of Rocky. Without Sylvester, nothing happens. He's given birth to the idea and we've had lots of fun during our cooperation. We're very convinced it will be successful.""
The all-singing, all-dancing play is expected to transfer to Broadway in 2013.