text: Angelique Kerber of Germany upset three-time defending champion Maria Sharapova 2-6, 7-5, 6-1 in the second round of the Porsche Grand Prix on Thursday. The top-seeded Russian won four straight games to clinch the first set but she made some errors to drop the second set and faded in the third. Top seed Maria Sharapova was beaten in three sets by Angelique Kerber of Germany . Sharapova, who had a first-round bye and had won her previous 13 matches in Stuttgart, also lost her world No 2 ranking after the defeat. She will be replaced by Simona Halep of Romania when the rankings are updated on Monday. Earlier, Madison Brengle of the United States upset third seed Petra Kvitova 6-3, 7-6 (2). Three-time champion Sharapova had won her previous 13 matches in Stuttgart . Kerber fought back from losing the first set to oust Sharapova at the Porsche Grand Prix . Fourth-seed Caroline Wozniacki won 7-6 (5), 6-1 against Lucie Safarova of the Czech Republic to reach the quarter finals. Brengle served for the match at 5-4 but Kvitova saved three match points to force a tie breaker. Brengle took a commanding lead and won her first match over a top-10 player with a backhand passing shot. Caroline Garcia of France, Ekaterina Makarova of Russia and Sara Errani of Italy also advanced.
target: Maria Sharapova lost to Angelique Kerber in Stuttgart on Thursday .
  The German fought back to claim a 2-6, 7-5, 6-1 victory .
  Sharapova will now be replaced by Simona Halep as the world No 2 .