Funny man Jimmy Fallon and all around fun guy Justin Timberlake busted out a "Single Ladies" dance at the US Open Wednesday night, and it was caught on camera.

Video: Epic history of Rap 6 by Fallon and Timberlake on 'Tonight Show'

People reports that the pair were sitting in the Emirates Suite as they watched Roger Federer take on Richard Gasquet, who later won in straight sets to move onto the semifinals. 

Related: Defending champ Marin Cilic next up for No. 1 Novak Djokovic at US Open

Watch the adorable impromptu tribute to Beyonce's ("best video of all time") below.