German Julia Goerges defeated world number one Caroline Wozniacki for the second time in little more than a week, sending the top seed out 6-4, 1-6, 6-3 in the third round of the ATP-WTA Madrid Masters on Thursday.
The 27th-ranked German had stunned the Dane 11 days ago to win a clay title in Stuttgart, and produced another winning performance to send Wozniacki packing.
Wozniacki is now into her 29th week as world number one but will need to lift her game next week in Rome if she is to have any chance of winning a career-first grand slam trophy.
The Dane has reached the final at five of eight events and owns three titles this season, the most on the WTA.
Goerges, only the second German to win Stuttgart, is making a solid Madrid debut and next plays the winner from Anastasia Pavlyuchenkova and French Open finalist Samantha Stosur in the quarter-finals.
Goerges advanced in just over two hours and needed treatment on a foot in the final set. She broke Wozniacki for 5-3 in the closing stages and served out the victory on the first of three match points.
Australian Stosur, seeded fifth, and China's sixth seed Li Na were due to play their matches later, with Li taking on Italian Roberta Vinci, a titleholder last weekend in Barcelona.