Behind the glitz and glamour of the U.S. Open, 16 strangers from around the globe are busily stringing tennis rackets for the top players in the world in a crowded room at the Billie Jean King Tennis Center in Flushing, New York. As the "official stringer of the U.S. Open," Wilson Sporting Goods is tasked with stringing rackets for everyone from Roger Federer to Serena Williams.

"Most of the guys in this room will string 35 to 40 rackets per day," said Todd Mobley, a stringer from Atlanta, who is working his 8th U.S. Open.

Becoming a Wilson stringer at the tournament is no easy task. Stringers are selected from all over the world, coming from as far as Japan, Australia and Argentina.

The stringing process takes about 15 minutes per racket and is then stamped with the famous Wilson logo and returned to the players. In a pinch, the stringers say they can string a racket in as fast as 11 minutes. They expect to set a record this year, stringing 500 rackets in one day.

Jessica Golden | CNBC