What rhymes with “Yo, Adrian!”?

The answer may lie with Lynn Ahrens and Stephen Flaherty, a Tony Award-winning songwriting team (“Ragtime”), who along with book writer Thomas Meehan are deep into a stage musical adaptation of the boxing-cum-romantic drama “Rocky,” the winner of the 1976 Academy Award for best picture.

The creators and producers, which include “Rocky” star and screenwriter Sylvester Stallone, held a private reading of the work in New York in April, according to Mr. Meehan and a member of the producing team, Barbara Darwall. In interviews on Wednesday, they described the reading as creatively successful and said work was continuing toward the goal of mounting the musical in Germany in the fall of 2012 — and then, they hope, bringing “Rocky” to Broadway in the spring of 2013.

Stage Entertainment, a European theatrical producer that now has the musical “Sister Act” on Broadway, is the lead producer, Ms. Darwall said. An email sent Wednesday to Michael Hildebrandt of Stage Entertainment was not immediately answered.

The project began about eight years ago, Mr. Meehan said, when Mr. Stallone called him about making a musical of “Rocky.” Mr. Stallone holds the rights to the story, Mr. Meehan and Ms. Darwall said.

“It’s been a long gestation period, but it’s come to be a work that we’re really proud of,” said Mr. Meehan, a three-time Tony winner for “Hairspray,” “The Producers,” and “Annie.” “There was some worry early on — could we really make a musical out of a boxing picture? Could you make Rocky sing and dance? But when we did the reading, people were very impressed, and we’re going forward.”

He described the show as a small-orchestra, small-cast production, with about five principal characters and a plot that tracked closely to the first “Rocky” movie. He added that Mr. Stallone was an artistic partner and producer, not a potential cast member.

“At first I thought, all the world needs is a ‘Rocky’ musical,” Mr. Meehan said. “But then I looked at the film. I thought it had beautiful construction and such high emotion, and it was a natural musical: There is a David and Goliath story, a Cinderella story, a love story between two outcasts. It’s less about boxing than about finding self-respect and finding your soul mate.”

Ms. Darwall said plans were in motion to produce the show in Germany around November 2012, and added that “Broadway is definitely a possibility after that.” Asked to describe the sound, mood, and tempo of the music, Ms. Darwall replied, “All I can say is that it’s a glorious score, telling an intimate relationship story. I think people will be really surprised.”

Movies becoming musicals are commonplace on Broadway today — “Sister Act,” “Priscilla Queen of the Desert,” and “Catch Me If You Can” all opened this season — but theatrical works about sports are more rare. Still, “Rocky” would not be the first boxing musical. In 1964 Sammy Davis, Jr., made his Broadway musical debut in “Golden Boy,’‘ with a score by the team who wrote “Bye Bye Birdie.” And Goodspeed Musicals, in Connecticut, is now mounting “Cutman: A Boxing Musical,” about a young Jewish fighter whose dreams are roiled when his title bout is scheduled on the eve of Yom Kippur.