Photos: A first look at your 2021 Australian Open semifinalists

Karolina Muchova advanced to her first major semifinal with a stunning comeback to oust World No.1 Ashleigh Barty, 1-6, 6-3, 6-2  at the Australian Open. The 24-year-old Czech will face US Open semifinalist Jennifer Brady on Thursday, with the winner set to make their maiden major final.

"I actually have one memory from here when I was a kid and got my first notebook," the No. 25 Muchova told reporters after the win. "I put it as a wallpaper Rod Laver, the stadium. I was just, like, I hope one day it would be nice to play there or to look at the arena or whatever. Now I just won a match and make it to semifinals. It's amazing."

Muchova has yet to lose a match in 2021, extending her record to 8-0 after her first career win over a World No.1. Muchova came into Wednesday's match riding the confidence of two big wins over No.6 seed Karolina Pliskova and No.18 seed Elise Mertens. Playing just her third main draw at the Australian Open, Muchova had yet to drop a set en route to her second major quarterfinal.

READ: 'I never had a Plan B' - How Muchova overcame injuries and financial struggles to make it on tour

Barty raced to a clean opening set in just 25 minutes. While the Aussie kept a clean sheet, hitting 6 winners to just 6 unforced errors, Muchova started sluggishly. The Czech hit 1 winner to 16 unforced errors and served at just 44 percent in the opening set.

Down a break at 2-1 in the second set, Muchova took a medical timeout after receiving a visit from the physio and the doctor. Struggling with dizziness in the heat, Muchova said the physio and doctor checked her vitals and worked to cool her down off court. 

Play resumed nine minutes later, and Barty struggled to regain her rhythm. Muchova broke the Barty serve for the first time to get back on serve at 2-2 and then forced Barty to save break points at 3-2 to hold. Facing break point at 30-40, Barty found her third ace of the match to get to deuce and then saved a second break point with a well-constructed point to earn a forehand miss. The Aussie went on to hold.

Looking to shorten rallies, Muchova stepped up her aggressive game plan. An all-court player with great touch and feel, Muchova's net play flourished and she began to flatten out her forehand to get Barty into a more defensive shell. 

Again Muchova put Barty's serve under pressure at 3-4, and while Barty did well to save another pair of break points, the World No.1 double-faulted at deuce and then misfired on a short forehand to give Muchova the break. Muchova held with ease off three straight errors from the Barty racquet, taking the set 6-3.

"I would have liked to have just been a little bit sharper the next game," Barty said, when asked about the pause in play. "Started well with the first point, just made a couple loose errors in that game. I think for the rest of the set, that was the story. Probably pressed a little bit trying to be overly aggressive.

"Had some breakpoints, I think it was that 3-All, that was probably a bit of a critical game in the momentum there for the second set."

Muchova continued to ride her momentum at the start of the final set. She broke Barty immediately at 15 and then held off the break-back. Barty earned two break points at 1-0, 15-40, but played two tentative points to give Muchova a chance to attack and wipe out both chances.

Barty earned a critical hold from 0-30 down to get on the board at 2-1. But Muchova remained the steadier player down the stretch. On the big points, Muchova was the one playing aggressively and taking her chances and she was rewarded accordingly. From 2-2, Muchova reeled off the final four games, including a gutsy close in the final game to save three break points to close the door on Barty's bid for a home Slam.

"I felt like I had small windows of opportunity probably midway through the second set and wasn't able to kind of regroup enough to be clear in the third set how I wanted to play," Barty said. "I think I just lost my way a little bit, which is disappointing without a doubt.

"I felt like I was in control of the match. I knew how I wanted to go about it, just lost my way a bit."

Perhaps the most pressing question afterward was what Muchova wrote on the courtside camera. 

"It's actually not a bug," Muchova said, when asked about her post-match doodle. "But everyone thinks it's a bug. I'm not really a good drawer.

"I don't have my coach, half of the team actually, I have them all home in Czech. We have a WhatsApp group. This is the picture of our WhatsApp group. It's an African sign, because it was not an easy start for us here. It means heartiness and toughness. It's called Wawa Aba and I draw it to tell them hi back to Czech."

Muchova's comeback over Barty was her third notable comeback win of her standout tournament. Against compatriot and practice partner Pliskova, Muchova ran off the last seven games from 0-5 down in the second set to win 7-5, 7-5 in the third round. Then, against red-hot Mertens, Muchova overcame a slow start to claw back from a 0-4 deficit to win 7-6(5), 7-5. Against Barty, Muchova would win 12 of the final 15 games to add her name to the Czech Republic's deep bench of Slam semifinalists. 

"I think I will have to bring my A-game to play with [Brady] because she is really playing amazing matches, having a good season, even the last season so far. I look forward to that one. I will try to play my best."

2021 Australian Open Highlights Day 6: Muchova stuns Pliskova