Ash Barty's Australian Open campaign is over following a stunning shift in momentum at Rod Laver Arena on Wednesday.
After the world No. 1 clinched the first set in lightning speed, her Czech rival fought back to secure an unlikely victory in three sets.
Tonight, world No. 2 Rafael Nadal will take on Greece's Stefanos Tsitsipas in a mouth-watering men's quarterfinal clash.
Defending champ's health revelation
Defending Australian Open champion Sofia Kenin was knocked out in round two and revealed today she had her appendix removed this week.
"I went to the tournament physician office on Monday, February 15th with acute abdominal pain," she wrote on social media. "I was evaluated by the tournament physician and referred to the hospital for further evaluation.
"Acute appendicitis was diagnosed following the completion of my CT scan. I had to have surgery and had my appendix removed on Monday, February 15, at Epworth Hospital Richmond.
"I want to thank everyone at Epworth Hospital Richmond for taking good care of me!"
Barty's classy response to saga
Australia's Ash Barty provided a classy response when asked about Karolina Muchova's decision to take a medical timeout in their quarter-final clash.
"It's completely within the rules for her to take it … that shouldn't be a massive turning point in the match," Barty told reporters after the defeat.
"I'm disappointed it did become a turning point."
Barty conqueror's startling admission
Czech tennis star Karolina Muchova has made a startling confession about the medical time-out which proved a turning point in Wednesday's victory over world No. 1 Ash Barty.
The Australian was dominating Muchova before the 10-minute break on Rod Laver Arena, ultimately halting her momentum in the Australian Open quarter-final.
After the win, Muchova was asked if she'd taken the time-out to have a pre-existing injury treated.
"I was a bit lost on the court and my head was spinning so I took a break. It helped me," Muchova said.
"No, it was more they just checked my (blood) pressure because I was a bit lost. I was spinning. So they cooled me down a bit with ice and it helped me."
Brady wins all-American clash
In an all-American clash on Rod Laver Arena, Jennifer Brady has toppled countrywoman Jessica Pegula to qualify for the semi-finals.
Brady secured a 4-6 6-2 6-2 victory to book her spot in Thursday evening's semi-final against Karolina Muchova.
"We are such good friends and I'm happy for her success and I know we will be having more tough battles," Brady said after the win.
"I've been putting in the hard yards with my trainer … ee are getting better every single day and every day is another opportunity."
Barty capitulates in quarter-final clash
Ash Barty's Australian Open campaign is over.
Barty took an early lead against Czech star Karolina Muchova in the quarter-final, winning the first five games in the opening set.
Barty needed just 14 minutes to secure a double break, making one unforced error in the first five games.
Barty clinched the first set in 24 minutes, during which Muchova made 13 unforced errors and just one winner.
The second set started in similar fashion, with Barty immediately breaking serve.
At 2-1, Muchova was examined by a trainer before taking an off-court medical timeout, and seemed like a different player when she returned nine minutes later, mustering her first break to put the set back on serve at 2-2.
Barty's unforced error count skyrocketed after her opponent's medical timeout, but managed to save two break points in her following service game.
The Aussie failed to convert two break points at 3-3, with Muchova then breaking serve at the other end.
Barty ultimately lost her first set of the tournament as the match headed towards a decisive third set.
Muchova started the final set by breaking serve as Barty's unforced error tally continued to rise.
The Queenslander then missed out on another two break points as the No. 25 seed took control of the match.
Muchova then secured the double break, with the ultimate fightback almost complete.
In what was ultimately the final game of the match, Barty couldn't convert three break points before Muchova ended the contest with an ace.
Barty vs Muchova score: 6-1 3-6 2-6
Victoria lockdown ends midnight
Victoria will emerge from a short, sharp "circuit-breaker" lockdown at midnight tonight.
Premier Daniel Andrews addressed the media this morning, revealing the good news.
"This will be a five-day, short, sharp circuit breaker," he said. "Restrictions will come off at midnight tonight."
Rod Laver Arena
1pm: Ash Barty (AUS)  v Karolina Muchova (CZE) 
3pm: Jennifer Brady (USA)  v Jessica Pegula (USA)
5pm: Andrey Rublev (RUS)  v Daniil Medvedev (RUS) 
9:30pm: Stefanos Tsitsipas (GRE)  v Rafael Nadal (ESP) 
How to watch
You can watch the action live on Sky Sport, or stream it via Sky Sport Now.