Serena Williams reacts to first sip of US Open's signature cocktail after decades of competing on the court

Serena Williams is back at the U.S. Open. 

But instead of emerging from one of the player's lockers at the Arthur Ashe Stadium's back of house, the six-time Grand Slam winner took in the action from the stands. Williams was on hand over Labor Day weekend as Day 7 of the final Grand Slam took place.

Unfortunately, Williams was at the prestigious tournament on the same day that last year's champion Coco Gauff fell and was knocked out of the tournament. But, since Williams was a spectator instead of a competitor...