The three-times defending champion Maria Sharapova was bounced out of the Porsche Grand Prix by Angelique Kerber of Germany 2-6, 7-5, 6-1 in the second round of the Suttgart tournament.
The top-seeded Russian, who had a first-round bye, won four straight games to clinch the first set but she made some errors to drop the second, and faded in the third. She held a 13-0 record in Stuttgart before the loss.
Sharapova will now lose the No2 ranking in the world to Simona Halep of Romania when they are updated on Monday.
Meanwhile, Madison Brengle of the United States upset the third-seeded Petra Kvitova 6-3, 7-6.