Caroline Wozniacki's hopes of replacing Simona Halep as world number one by winning the Madrid Open were dashed when she suffered a shock defeat in the third round.
Wozniacki was demolished 6-2 6-2 by Kiki Bertens, who is 20th in the rankings, in just over an hour.
The reward for Bertens is to face another Grand Slam winner in Maria Sharapova, who overcame Kristina Mladenovic of France 6-3 6-4.
There was no upset against defending champion Halep as the Romanian top seed cruised to a 6-1 6-4 victory over Kristyna Pliskova.
She will face Karolina Pliskova in the quarter-finals after American Sloane Stephens was dispatched 6-2 6-3.