World No.1 Ash Barty's bid to become the first homegrown Australian Open champion since 1978 has ended in a 1-6 6-3 6-2 quarter-final defeat to Karolina Muchova.
The Czech 25th seed rallied after a long medical timeout in the second set to secure a place in her first Grand Slam semi-final.
Barty wasted no time in stamping her authority on the contest and looked to be coasting, when she conceded only six points en route to a 5-0 lead in just over a quarter of an hour, wrapping up the first set soon afterwards.
Muchova had treatment at her chair early in the second set and then took a medical timeout, returning to court revitalised and ready to take the match to the former French Open champion.
"I started feeling a bit lost by the end of the first set," said Muchova. "Ash was playing very good, she made almost no mistakes.
"My head was spinning, so I took a break... it was more they just checked my pressure.
"I was a bit lost, I was spinning. They cooled me down a bit and it helped me."
Barty had no complaints about the medical timeout that turned the match on its head.
"It's within the rules," Barty said. "She's within her rights to take that time. If she wasn't within the rules, the physios and the doctors would have said so.
"I was disappointed that I let that become a turning point. I'm experienced enough now to be able to deal with that."
Although not quite as dominant as the Australian had been in the first set, the Czech levelled up the match at 1-1 to become the first player to take a set off the top seed at this tournament.
Barty continued to carve out chances on Muchova's serve, but failed to convert them and her error count soared, as she tried to finish points too early to wrest back the momentum.
Muchova hit 17 winners over the match and defied her nerves to serve out for the win at the first attempt, sealing her place in the last four with an ace.
"I just tried to put a ball in and go for it, play a bit faster, go to the net," Muchova adds. "I'm happy that I handled it well."
The canned applause piped into the arena in the absence of fans appeared to taunt Barty, who would have been guaranteed passionate support for her semi-final, had she made it through after Melbourne's coronavirus lockdown was lifted.
Muchova will face Jennifer Brady for a spot in the final, after the American battled through her frustrations to overhaul friend and compatriot Jessica Pegula 4-6 6-2 6-1 to reach her maiden Australian Open semi-final.
Brady, the 22nd seed, was a picture of anguish early in the clash on a stifling day at Rod Laver Arena, but gradually dialled in her power game, before crushing Pegula in the final set.