Hampton, Ranked 54th, Upsets Kvitova PARIS - Jamie Hampton of the United States shrugged off a tumble onto the red clay that cost her one match point and bore down moments later, completing a 6-1, 7-6 (7) upset of seventh-seeded Petra Kvitova of the Czech Republic on Saturday. Hampton, unseeded here and ranked 54th, fell while racing to reach a drop shot to her backhand side. She quickly brushed the dust from her right arm and shoulder, then, two points later, outmaneuvered Kvitova in a short rally that ended the tense, hour-long final set at the French Open. Hampton was asked what crossed her mind after ending up in the dust. "Just trying to run down that ball," Hampton said with a chuckle, "or die trying. I didn't want to give her another look at another point. Hampton followed three other American women into the fourth round: Serena Williams, Bethanie Mattek-Sands and Sloane Stephens. Hampton weathered a barrage of 21 winners by Kvitova, who broke Hampton's serve three times. But Hampton kept pace, racing from side to side and breaking her opponent's serve five of the seven times she held a break point. "The important points she played better than me," said Kvitova, who was ranked second in the world in 2011. She offered no explanation for her first-set performance other than to cite Hampton's aggressive play. "I really didn't know what was happening," she said. "I think I caught her a little bit off guard," Hampton said, "and I don't think she was on her game." Hampton declared the victory "the best" of her career. In Australia in January, Hampton pulled Victoria Azarenka of Belarus into a third set before losing, 6-4, 4-6. The third-round match convinced Hampton that she was on track to scoring a breakthrough, she said. Azarenka, currently ranked No. 1 in the world and seeded third here, gained the fourth round with a three-set victory over Alize Cornet of France. Azarenka is scheduled to face unseeded Francesca Schiavone of Italy, who upset 13th-seeded Marion Bartoli of France in straight sets.