Today's Morning Edition music is the Elton John tune "Philadelphia Freedom."
In the 1970s, John befriended tennis star Billie Jean King and frequently attended her World Team Tennis matches.
King had a special warmup suit with her team's logo made for him, and in return, John promised to create a song for the team.
The resulting tune topped the charts 40 years ago Monday. Bernie Taupin, who wrote the lyrics, said they have nothing to do with tennis except for the title. In 1974, King played for the Philadelphia Freedoms.