Justin Timberlake and Jimmy Fallon Totally Won the U.S. Open With Their 'Single Ladies' Dance

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Following their Tonight Show reunion, best buds Jimmy Fallon and Justin Timberlake took in a U.S. Open match together on Wednesday -- and showed off their dance moves too!

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The BFFs were watching Roger Federer’s quarterfinal match against Richard Gasquet from the Emirates Airline suite when the sound system at Flushing Meadows apparently began playing Beyonce. Then, this happened:

Fallon and Timberlake could resist the urge to dance along to "Single Ladies (Put a Ring on It)," in pretty impressive synchronization, we might add!

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The best buds’ dance moves took us back to one of Timberlake’s legendary Saturday Night Live appearances. Remember when he, Andy Samberg, and Bobby Moynihan filled in as Queen Bey’s backup dancers?

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Check out Fallon and Timberlake perform another "History of Rap" on The Tonight Show Wednesday night, and see even more pics of J.T.'s new baby: