As Labor Day and the unofficial end of summer approach, the Song of the Summer has yet to be crowned. It's also something that remains unresolved at this year's U.S. Open.

"There's not really one single song," said Dieter Ruehle, who has been spinning tunes during the Open as the Arthur Ashe Stadium disc jockey since 2006. Ruehle, who works as the music director at Staples Center in Los Angeles, is also the DJ during Lakers and Kings games.

On Tuesday, after Roger Federer won his match on Ashe, Ruehle cued up Pharrell Williams's "Happy."

"Sometimes it just works its way naturally," Ruehle said. "That might stick if he wins again and the song fits the mood."

"Fancy," the hit song by Australian rapper Iggy Azalea, has dominated the pop charts this summer, but so far at this year's Open, it's barely been heard.