Justin Timberlake And Jimmy Fallon Hilariously Danced To 'Single Ladies' (Video)

Despite being one of the biggest annual professional sporting events, the US Open is a pretty reserved environment.

Occasionally (last year), first time attendees (me) have to learn the hard way (loud shushing) the Open is not a place for exuberance; it's a place for drinking martinis out of plastic coupes and insinuating clapping (but not actually clapping).

These rules may not apply to Jimmy Fallon and Justin Timberlake, who, during a music break in Arthur Ashe Stadium, broke out their best Yoncé moves to “Single Ladies (Put a Ring on It).”

In a video from Wednesday's event, Fallon wears his signature, self-satisfied, I-just-farted grin, and Timberlake looks determined to prove he hasn't forgotten the moves he learned dancing with King Bey on "SNL."

All the Single Ladies are out tonight at the #usopen @jimmyfallon @jtimberlake pic.twitter.com/lXCzXo8XCH — US Open Tennis (@usopen) September 10, 2015

The famous besties relaxed together at the event after filming their sixth installment of “History of Rap," which aired on "The Tonight Show" Wednesday evening.

Citations: Jimmy Fallon & Justin Timberlake Dance to Beyonce's 'Single Ladies' at US Open (Bleacher Report)