"Rocky - The Musical", the song-and-dance version of the iconic movie boxer's rise to the world title, hit the stage in Germany Sunday with both reigning champion Wladimir Klitschko and Hollywood heavyweight Sylvester Stallone in its corner.
Klitschko, the undisputed world heavyweight champion, and Stallone, who wrote the screenplay and starred in the 1976 hit movie, both lent their support to the staging, which will have its world premiere in Hamburg, northern Germany.
Although the musical is in German, Vienna-based American actor Drew Sarich plays the lead role in the story of the club fighter who rises to defeat fictional world champion Apollo Creed.
Stallone was part of the casting process and opted for Sarich, who has punched his weight in lead roles in German before, while Dutch actress Wietske van Tongeren plays the role of Rocky's shy wife Adrian.
Hamburg-based Stage Entertainment, which brought both "The Lion King" and "Tarzan" to the stage, have adapted the original script with 20 new songs packed into the musical and 20 tonnes of steel used for the set.
"Rocky is not about boxing, it's about the longing for dignity and the desire to be happy," said the 66-year-old Stallone, who will attend the evening premiere along with Klitschko.
"To find a guy like Rocky is very difficult.
"This was a real challenge for the casting team. I saw a lot of candidates on video and I was surprised about the great talent pool in Germany."
The original cult "Rocky" movie won three Oscars in 1976, for best picture, best director and best film editing, while Stallone played the lead role in a total of six Rocky films.
Around 15 million euros ($19 million) have been invested in the stage adaptation with a special sound system fitted in the Hamburg auditorium.
The audience is ringside for the final scene to capture the atmosphere of a world title fight.
"The fans are sure to be thrilled," said Hamburg-based Wladimir Klitschko, a co-producer along with brother Vitali, the WBC heavyweight champion.
"Rocky is just a normal person. He wasn't very confident, basically a loser, but he fought his way up.
"Whether you're a man or woman, in sport or in all sections of society, everyone can manage it and be successful," Klitschko said.
"Like Rocky said: 'Adrian, I did it!'"