It was another day of high-profile casualties at the Madrid Open as Victoria Azarenka withdrew through injury and defending champion Petra Kvitova crashed out.
Azarenka had not lost on the WTA Tour since Acapulco in February, but the fourth seed was forced to pull out during warm-ups for her third-round encounter with qualifier Louisa Chirico because of a back problem.
Meanwhile Kvitova's defeat to Daria Gavrilova means none of the top five seeds remain in the tournament, with Simona Halep the highest-ranked player left in the competition.
Sixth seed Halep had no difficulties in beating 10th seed Timea Bacsinszky 6-2 6-3 but the shocks kept on coming as eighth seed Carla Suarez Navarro lost in three sets to Samantha Stosur.
AZARENKA OUT AFTER TWEAKING BACK
Two-time Australian Open champion had been in blistering form ahead of her scheduled meeting with Chirico but opted to play it safe after tweaking her back.
Azarenka said she suffered the injury in her first-round win over Laura Robson and had battled through it in beating Alize Cornet.
However, with the French Open on the horizon, she will now undergo tests before deciding whether she will compete at the Internazionali d'Italia next week.
Chirico now faces a quarter-final meeting with Gavrilova.
GAVRILOVA ENDS KVITOVA DEFENCE
Kvitova saw off world number Serena Williams en route to glory in the 2015 Madrid Open, but was never able to find her rhythm against Gavrilova.
Gavrilova emerged victorious 6-3 6-4 after one hour, 42 minutes of play on clay in the Spanish capital as the Australian eyes a first WTA singles title of her career.
Fifth seed Kvitova, who had been dealing with an abdomen strain coming into the event, said: "I think Daria really played a solid match. I couldn't put everything together out there - I was still dealing with the pain from Stuttgart.
"I couldn't really practice for a week. I'm glad that I won two matches and I'm glad that it feels like it's getting better, so hopefully I can start to do more fitness and tennis practice."
HALEP HAMMERS BACSINSZKY
A winner at the Grand Prix de SAR La Princesse Lalla Meryem last week, Bacsinszky came into her third-round match with Halep on the back of seven straight wins.
But that run was brought to an end in emphatic fashion by the Romanian, with 2014 French Open finalist Halep needed just an hour, 12 minutes to progress to the last eight.
"I like more to play on clay," Halep said when asked how she was able to avenge her loss to Bacsinszky at the Miami Open.
"I changed tactics. I played less power today and I just tried to mix up the game, to be more creative on court, and to open the court better, to play more on her forehand.
"So I did a good job, and I think I adjusted my game very well to hers."
STOSUR COMEBACK STUNS SUAREZ NAVARRO
Eighth seed Suarez Navarro joined Azarenka and Kvitova in exiting the tournament as she fell victim to an excellent fightback from 2011 US Open champion Samantha Stosur.
Stosur trailed by a set and a break in the second but recovered to force a decider.
The Australian then displayed her powers of resiliency again by coming back from a break down in the third to prevail 4-6 6-2 6-3.
Qualifier Patricia Maria Tig beat Madison Keys as she joined compatriots Halep, Irina-Camelia Begu and Sorana Cirstea in the quarters, with Slovakia's Dominika Cibulkova also going through.
ALL-ROMANIAN AFFAIR HEADLINES THURSDAY
Halep will face countrywoman Begu in the quarter-finals. Cibulkova, Gavrilova and Stosur are also in action on Thursday against Cirstea, Chirico and Tig respectively.