PARIS — At the outset, Serena Williams was grimacing and cursing and, worst of all, losing by a lot. Then, suddenly, the 19-time Grand Slam singles champion was putting shots right where she wanted, imposing her will as only she can. And the only anger Williams displayed was directed at her opponent, Victoria Azarenka, while they traded gestures and words over the chair umpire's decision to replay a key point.