Ashleigh Barty, Sloane Stephens and Coco Gauff were all knocked out of the Charleston Open quarter-finals on Friday.
World number one Ashleigh Barty provided the biggest shock after she was knocked out of the tournament by unseeded Spaniard Paula Badosa Gibert, with the Australian winning just 51 per cent of her points on first serve on her way to a 6-4 6-3 defeat.
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Meanwhile, Badosa saved 12 of the 14 break points she faced in her first ever victory over a top-20 ranked opponent on the tour.
"I have watched Ash a lot. When I watch her on TV, I always said to my coach, my goal is to someday play against her," she said following her victory.
"I'm still a little bit shocked. I can't believe what just happened."
Badosa Gibert's shock sends her into the semi-finals to face Veronica Kudermetova, who knocked out another former Grand Slam winner by beating 2017 US Open champion Stephens.
Kudermetova, currently ranked 34th in the world, landed just 49 per cent of her first serves on her way to a 6-3 6-4 victory over her illustrious opponent.
The Russian, who is yet to make it past the third round of a Grand Slam, proved clinical winning four of five break points while Stephens converted just two from seven.
Danka Kovinic goes up against Ons Jabeur in the other semi-final. Jabeur defeated Gauff 6-3 6-3 as the American made a whopping 13 double faults, while Kovinic beat Yulia Putintseva in a 6-7 7-5 6-1 thriller.
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