Dominika Cibulkova suffered a shock straight-sets defeat at the hands of Oceane Dodin at the Madrid Open on Tuesday.
In a week that has seen top players tumbling in the Spanish capital, 2016 runner-up Cibulkova's 6-2 6-4 loss to Dodin left only five seeds remaining in the women's draw.
The Slovakian fourth seed had come through a challenging first-round encounter against Jelena Jankovic, but would have hoped for a smoother ride against the world number 63.
However, three breaks in the first set and two in the second were enough to send Dodin - claiming her first win against top-10 opposition - through to the third round, where she will meet fellow French player Kristina Mladenovic.
Meanwhile, defending champion Simona Halep secured her progression by battling past the spirited Roberta Vinci.
CIBULKOVA ALL AT SEA
With so many seeds having already been eliminated, the remaining top-16 players will have fancied their chances of going all the way in Madrid - particularly Cibulkova given her performance here last year.
However, she was well beaten by 20-year-old Dodin, who produced a powerful display to take her place in the next round.
"I'm very proud of myself," said Dodin. "I had stress but I had to be aggressive and have a big serve. Maybe it was the best match of my career."
HALEP FIGHTS BACK
Halep suffered a scare as she kept her bid to retain the Madrid Open title on track, eventually winning 6-3 2-6 7-6 (7-2).
"Her game is not easy to play," said Halep. "Her slices are very difficult to return. She was hitting pretty strong also with the forehand today, serve, everything. She played unbelievable.
"I was close to losing the match, but I stayed strong. I stayed focused. I didn't give up. That makes this match much bigger for me. It means a lot."
Halep now faces Sam Stosur, who triumphed 6-3 7-5 over Mariana Duque Marino.
Elsewhere, there were wins for Coco Vandeweghe, Wang Qiang, Irina-Camelia Begu, Sorana Cirstea, Misaki Doi and Kiki Bertens.