Serena's injury forced her to pull out of her second-round match with Taiwan's Chan Yung-Jan. At the moment she gave up, she was leading 5-3.
"I've been playing a lot on the clay. I was just sliding a lot and I think I just slid too far," Serena said after the match.
Now it's certain that we won't have the pleasure of watching a clash between the Williams sisters in Charleston, even though it was likely that they would meet in the third round. Their last encounter was at the 2005 US Open.
(via BBC Sport)