Tournament favourite Petra Kvitova was one of three seeds to exit the Qatar Open at the quarter-final stage on Thursday as Carla Suarez Navarro prevailed 3-6 6-0 6-3 to cause an upset.
Top seed Kvitova - who also lost to the Spaniard in Dubai last week - looked to be cruising into the last four after taking the first set in comfortable fashion, but she lost 10 successive games as the match was turned on its head.
The Wimbledon champion saw all aspects of her game desert her with serves devoid of power, drop shots lacking accuracy and wayward groundstrokes.
She attempted a brief revival late in the deciding set, but ninth seed Suarez Navarro had done enough to allow her to triumph.
Kvitova was not the only seed in trouble at the hard-court event, with Caroline Wozniacki and Agnieszka Radwanska also failing to reach the semis.
Wozniacki – the third seed – endured a frustrating match against Victoria Azarenka, the Belarusian continuing her recovery from a nightmare 12 months with injury to win 6-3 6-1.
A dramatic start to the match saw five consecutive breaks before Azarenka took control, while Wozniacki's frustrations at some line calls clearly affected her play.
With Azarenka remaining calm throughout she was able to take full advantage, the world number 48 winning the final five games to book a semi-final against Venus Williams.
The veteran sealed her place after a 6-4 1-6 6-3 victory over fourth seed Radwanska.
Andrea Petkovic completed the seeds' miserable day, going down 6-2 6-1 to Lucie Safarova in a little over an hour.