World number one Iga Swiatek suffered a quarter-final exit at her home tournament, the Poland Open, after losing in three sets Friday to France's Caroline Garcia.
French Open champion Swiatek had not lost on clay in over a year before going down 6-1, 1-6, 6-4 to the 45th-ranked Garcia.
Swiatek was 18-0 on clay this season, winning titles at Stuttgart, Rome and Roland Garros, and had only dropped two sets on the surface in 2022.
"It was a very important match and I tried to be ready for it," said Garcia.
"I started very strong, putting a lot of pressure on her. As soon as I got a bit lower-intensity, she came back very strong, and that's what is happening against a top player.
"I stayed positive, I kept believing in my game and the way I wanted to play, and the third set was definitely very good tennis."
Garcia will play Italy's Jasmine Paolini for a place in the Warsaw final. Paolini recovered from a poor start to defeat Switzerland's Viktorija Golubic 1-6, 6-2, 6-2.
Ukraine's Kateryna Baindl faces Ana Bogdan of Romania in the other semi-final.