Marketa Vondrousova on Friday reached her first semi-final since clinching the Wimbledon title last July when she stunned world number two Aryna Sabalenka at the Stuttgart clay-court tournament.
The sixth-seeded Czech came through 3-6, 6-3, 7-5 in just over two hours.
It was the 24-year-old’s first win over Sabalenka in six years after losing four in a row between 2018 and 2023.
Australian Open champion Sabalenka had been attempting to make the Stuttgart final for a fourth successive year.
The powerful Belarusian crunched 35 winners to Vondrousova’s 17, but committed 48 unforced errors compared to 19.
Wimbledon champion Vondrousova crucially converted seven of eight break points while Sabalenka only capitalised six times from 15 opportunities.
Vondrousova will face either third-ranked Coco Gauff, the US Open champion, or Marta Kostyuk of Ukraine for a place in Sunday’s final.
Earlier fourth-seeded Elena Rybakina defeated Jasmine Paolini 6-3, 5-7, 6-3.
She will face either two-time defending champion and top-ranked Iga Swiatek or former US Open winner Emma Raducanu for a place in the final.
