Bar Refaeli and Bradley Cooper kick off the U.S. Open

What better way to signal the beginning of a weeks-long competition of world class athletes than a friendly game of celebrity tennis?

Bradley Cooper and Bar Refaeli joined Raphael Nadal, Maria Sharapova, Roger "Vogue" Federer, and Serena Williams in the Nike Primetime Tennis Knockout at Pier 54 in New York City. (I feel as though I should be paid for saying all that.)

No word on which team of doubles won. And if score was actually kept, no one thought it relevant to print. (If you know the winning doubles team, tell us.) What was explained in meticulous detail, however, was the color and cut and Bar Refaeli's sportswear. It was tight and black and short, everyone.

This year's Open runs from Aug. 26 to  Sept. 12 ; stay tuned to find out which one of your favorite "seeds" will take the men's and women's title.

Via Huffpo