Timberlake, Jimmy Fallon entertain US Open crowd with impromptu Beyonce dance routine

Singer Justin Timberlake and comedian Jimmy Fallon broke into an impromptu gig by dancing to pop star Beyonce's hit song "Single Ladies" at the US Open in New York.

The 34-year-old "Mirror" hitmaker and best friend Fallon, 40, who were watching Roger Federer take on Richard Gasquet, started dancing when the song played over the stadium's speakers, reported Entertainment Weekly.

Fallon was the first one to get up from his seat and dance, followed by Timberlake who matched steps with him. While the comedian could not control his laughter, Timberlake kept a poker face while dancing.

Here's Jimmy Fallon & Justin Timberlake dancing in the stands to Beyonce on the arena screen pic.twitter.com/c1uGWRkEJZ

— The Cauldron (@TheCauldron) September 10, 2015

This is not the first time Timberlake has shown love for "Single Ladies". In 2009, he participated in an SNL sketch built around the song with Beyonce herself.