The music director of the Louisville Orchestra and the guitarist from rockers My Morning Jacket on Friday released a genre-merging tribute to late boxing legend Muhammad Ali.

Inspired by Ali's quote that he would "float like a butterfly, sting like a bee," the song is entitled "Float Rumble Rest" and was written in the hours after his death on June 3.

The song stretches over more than eight minutes, opening with a modern and lively piano before blending into organ and a melancholy guitar line.

Teddy Abrams, the 29-year-old music director of the Louisville Orchestra, had led an impromptu tribute to Ali the day after his death, bringing a keyboard to lead mourners in singing "Amazing Grace" outside the Muhammad Ali Center.

Gill Holland, the founder of sonaBLAST! Records based in this city in the southern state of Kentucky, ran into Abrams shortly afterward and asked him about writing a song.

Jim James of the Louisville-based rockers My Morning Jacket joined on guitar.

"Learning from Ali's story and message, I've found both personal inspiration and a call for the world to be a far more peaceful, empathetic and tolerant place," Abrams said in a statement.

"I hope that, in a small way, this piece of music can help keep his beautiful story alive and his legend may help guide the species in future generations," he said.

The song went on sale on iTunes, with all proceeds to go to the Muhammad Ali Center which highlights the boxer's life and encourages his principles including charity, respect and spirituality.

Abrams revealed just weeks before Ali's death that he was working on an orchestral work inspired by the sporting legend's life to premiere next season.

Born as Cassius Clay in 1942, Muhammad Ali was one of the greatest athletes of the 20th century. He shocked white America by converting to Islam and refusing to serve in the Vietnam War, but became a respected spokesman for tolerance and civil rights.