By the third set of her quarterfinal match with American Sloane Stephens, Serena Williams was frustrated. She needed medical attention for rogue back spasms midway through the match. It hindered her game, and Serena ended up dropping that second set to Stephens, a minnow she normally would have crushed.
2. Early in the third set, Stephens is serving to go up 2-1. Perhaps sensing the match is slipping away, Serena prepares to return the serve.