Unheralded Czech teenager Linda Noskova stunned world number two Ons Jabeur Saturday to make her first-ever final at the Adelaide International, dealing the Tunisian a demoralising blow ahead of the Australian Open.
The 18-year-old qualifier showed experience beyond her years to win 6-3, 1-6, 6-3 and set up a clash with world number five Aryna Sabalenka in Sunday's decider.
American Sebastian Korda booked a spot in the men's final, with either Novak Djokovic or Daniil Medvedev awaiting him.
Noskova upset two-time Australian Open champion Victoria Azarenka enroute to the semis with that win her fifth in Adelaide in only her sixth tour-level event.
"I don't think either of us played 100 percent and I'm glad I got that last point to win, just really glad to play like this," said the world number 102.
"I'm just going for it 100 percent all the time, just trying to push through."
Jabeur had treatment on a lower back problem at 2-5 in the first set, but she bounced back to easily take the second before struggling in the third.
Unseeded Korda, son of former world number two Petr Korda, was in charge 7-6 (7/5), 1-0 of his match when Japan's Yoshihito Nishioka called for a medical timeout before pulling out of the match.
Nishioka received treatment on his upper right leg and was forced to retire, casting a shadow over his preparations for the Australian Open this month.
"Very excited for the way I'm playing and a lot of confidence leading into the big one (final)," said Korda, 22, who won his first and only title on clay in Parma in 2021, while making two finals last year.
"Excited to play either one (Djokovic or Medvedev). It's always a great thing to learn from different kinds of players," he said of Sunday's final.
"It's going to be a great learning experience whatever the outcome and, you know, I'm going to go for the win."
Top seed Djokovic, who has an ominous 21-1 record since September, takes on Russian third seed Medvedev in an evening semi-final.
The world number five Serbian holds an 8-4 edge in their head-to-head, with 10 of the 12 showdowns coming on hard courts.
Sabalenka surged into the women's final by crushing Romanian veteran Irina-Camelia Begu 6-3, 6-2.
"I'm happy with the level I played today," said the Belarusian, who is targeting an 11th career title and a first since Abu Dhabi and Madrid in 2021.
"She's playing a different style so super happy that I was able to be in the match.
"We did everything right in the pre-season, I think this is the key," she added in explaining her good early-season form, where she is yet to drop a set.
Begu had beaten seventh seed Jelena Ostapenko and fourth seed Veronika Kudermetova enroute to the last four, but was no match for the power of the Sabalenka serve and her ferocious returns.