World No 1 Aryna Sabalenka suffered a shock 2-6 6-2 7-6 (8-6) defeat to Hailey Baptiste to be knocked of the Madrid Open at the quarter-finals.
It was 30th seed Baptiste's biggest win of her career to date, her first over a top-five player, as she saved a staggering six match points before clinching victory.
Sabalenka - a three-time Madrid champion - dominated the early exchanges, forcing two service breaks on her way to taking the opening set 6-2.
But Baptiste grabbed two breaks of her own at the start of the second and although Sabalenka pulled a break back to make it 4-2, she'd swiftly drop serve again as a 6-2 reverse forced a deciding set.
Service breaks were traded twice more in the deciding set before Baptiste saved five Sabalenka match points on her serve on the way to winning the 10th game.
Baptiste then broke for a 6-5 advantage, but failed to serve out the win as Sabalenka broke back to make it 6-6 before bringing up a sixth match point up 6-5 in the ensuing tiebreak.
However, Baptiste reeled off the next three points to complete a dramatic victory after two hours and 32 minutes, setting up a semi-final meeting with Mirra Andreeva after the world No 9 beat Canada's Leylah Fernandez 7-6 (7-1) 6-3 earlier on Tuesday.
"Incredible. Super proud of myself," the 24-year-old Baptiste said. "It was a super tight match, 7-6 in the third. Had to fight off match points; I'm really happy right now.
"It just shows me where my game lies. I've always believed it. Now I'm starting to put it into action and the world is seeing it as well."
Defending-champion Sabalenka's defeat is the latest upset at the WTA 1000 clay tournament that has seen the top seven seeds all knocked out.
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