Magda Linette will meet fifth seed Aryna Sabalenka in the Australian Open semi-finals after she beat Karolina Pliskova to continue her dream run.
The Polish world number 45 had previously never gone beyond the third round of a Grand Slam in 29 attempts.
But she produced a fearless display in a 6-3 7-5 win over Czech two-time major finalist Pliskova on Rod Laver Arena.
Belarusian Sabalenka defeated Croatia's Donna Vekic 6-3 6-2 to reach her fourth Grand Slam semi-final.
"I'm so emotional. I can't really believe it. It is really a dream come true. I'm super grateful and happy," Linette, 30, said.