Barty bombs out: The moment that will haunt Ash
It was all going to plan for Ash Barty until one specific moment in the early stages of the second set. Some of the biggest names in the sport could not believe what came next.
A set and a break down, Barty's opponent Karolina Muchova took a medical time out.
Whatever happened during the break, it transformed her performance.
Commentators and onlookers were stunned by the turnaround.
"I tell you what, if I'm ever having a bad day, I'm calling that WTA trainer to help. Miracle worker," Jim Courier said.
"It's incredible. Before the medical timeout, look how dominant Barty was across the board. The short points, mid points, long points, sweeping almost all of them. Afterwards, it's flipped.
12.15pm What happened during THAT medical timeout?
Muchová has spoken on the break that changed the match.
"I started feeling a bit lost by the end of the first set. She played almost like no mistakes, it was very tough and I was a bit lost on the court and my head was spinning so I took a break.
"It helped me. I tried to get back, played a bit faster rallies so we don't play the long ones as in the first set and it worked well.
"It was more (to) check my pressure because I was, as I said, a bit lost, you know, I was spinning. They cooled me down a bit with ice and it helped me."
12.10pm: Barty crashes out of Open - 6-1 3-6 2-6
Genuine shock here at Melbourne Park.
The dream of having a home slam winner is over for another year with Barty crashing out of her quarter-final 6-1 3-6 2-6.
Muchová's medical timeout was completely within the rules. But there is no doubt the match completely flipped after that 10 minute break.
What a turnaround on Rod Laver Arena. I don't think anyone can believe what we've just seen.