World No. 1 Ashleigh Barty's quest to become the first Australian to win their home Grand Slam since Chris O'Neil in 1978 is over after she was beaten in the quarterfinals by 25th seed Czech Karolina Muchova on Wednesday.
Barty, who hadn't dropped a set on her way into the quarterfinals, started strongly against her lower-ranked opponent, but fell in three sets, 1-6, 6-3, 6-2 on Rod Laver Arena.
The Australian opened up an early break in the second set to lead 2-0 before Muchova took an extended injury timeout and left the court. Upon returning, Muchova won six of the next seven games to take the set and force a third.
Barty then went behind a break in the first game of the deciding set and was unable to regain ground or her composure, falling to the Czech in one hour and 58 minutes.
After dominating the first set hitting six winners to Muchova's one, the world No. 1 hit 19 unforced errors in the second set to her opponent's nine, and then a further 12 in the third to seal her exit.
Muchova told the host broadcaster after the match that while she didn't take the medical timeout for a physical issue, she did feel "lost" and needed to clear her head.
"I was lost at the end of the first set, my head was spinning so I took a break and it helped me," she said on-court.
Speaking to the press following the loss, Barty said it wasn't her business what her opponent took the timeout for, saying the match was "a massive learning curve" for her going forward.
"I didn't hear what she said when she called for the [timeout], it's not my decision. That's within the rules, for me that's not really my concern what she took the medical for," the world No. 1 said.
"When you look down the other end she was taking her time quite often. It was a warm day.
"[But we will] go through everything. We learn through all of the experiences that we've had over the past two or three weeks. We just look back on it, we learn.
"Overall we take the positives that have come out of this last two or three weeks. Being back on the tour has been fantastic. I've loved every second, even though at times it is frustrating. That's the name of the game. That's the sport that we play."
Barty said she was scheduled to appear at tournaments in the Middle East in coming weeks, but wasn't sure what her broader 2021 calendar was looking like given the "health risks" involved with overseas travel and the likelihood of having to quarantine upon return to Australia.
"We've planned and we've entered to play a few of the tour events coming up in the Middle East," she said.
"Right from the get-go, obviously it's the first time we've looked to travel for quite some time now. We'll sit back and kind of go through all of the health risks that are at this stage and to where we're going, then we just work from there."
Muchova will face the winner of Wednesday's second quarterfinal - an all-American affair between 22nd seed Jennifer Brady and world No. 61 Jess Pegula.