Embedded Player At the U.S. Open semifinal on Saturday, Serena Williams launched a profanity-laced tirade at a lineswoman who called a foot fault, resulting in a double fault for Williams. That moved her rival, Kim Clijsters, one point away from victory. The outburst cost Williams the match. Jeff Ponder, a former tennis line judge, says the rule states that you cannot in the motion of your serve step on the baseline.