Teenage Czech qualifier Linda Noskova upset former world number one Victoria Azarenka to set up a semi-final showdown with Ons Jabeur at the Adelaide International.
In a match lasting almost three hours, Noskova triumphed 6-4 6-7 (3-7) 7-6 (8-6) to continue a dream run in Australia.
Noskova has already beaten third seed Daria Kasatkina in Adelaide and, on only her sixth appearance in a WTA main draw, has won five straight matches.
Further progress will be no easy feat, with top seed Jabeur – a losing finalist at Wimbledon and the US Open in 2022 – grinding out a 7-6 (7-5) 7-5 win over Ukrainian Marta Kostyuk.
On the other side of the draw, second seed Aryna Sabalenka held off a resurgent Marketa Vondrousova to win 6-3 7-5. The Belarusian had led 4-1 in the second set before losing four of the next five games and failing on match point prior to finally seeing it out.
Irina-Camelia Begu defeated fourth seed Veronika Kudermetova 7-5 6-4 to set up a last-four clash with Sabalenka.
At the ASB Classic in Auckland, top seed Coco Gauff outclassed Zhu Lin 6-3 6-2, winning 90 per cent of first-serve points, firing down eight aces, and not giving up a single break point.
Seventh seed Danka Kovinic also won 6-3 6-2 against Viktoria Kuzmova to set up a semi-final clash with Gauff, while world number 95 Ysaline Bonaventure ousted third seed Leylah Fernandez 6-4 6-2 to reach a first Tour-level semi-final where Rebeka Masarova awaits.