Top-ranked Ash Barty was upset Wednesday by No. 25-seeded Karolina Muchova in the quarterfinals at the Australian Open, 1-6, 6-3, 6-2.
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.
Muchova earned her first semifinal berth in a Grand Slam, and her comeback win ended Barty's bid to become the first Australian woman to win the title in Melbourne since Chris O'Neil in 1978.
Muchova's opponent Thursday will be the victor of the last quarterfinal, an all-American matchup between No. 22-seeded Jennifer Brady and unseeded Jessica Pegula.
There was no sign of trouble for Barty early on as the top seed dropped just seven points while charging to a 5-0 lead in the first set.
However, Muchová took a nine minute medical timeout after the first set - before staging a comeback to gain full control to win the second set 6-4 and clinched the decider 6-2. Ash started very good. "It will be a brilliant match", Barty said, describing her opponent - also 24 years old - as a "hell of a player". I was a bit lost on the court and my head was spinning, so I took a break.
"So they cooled me down a bit with ice and it helped me". "I know she's got the ability to manoeuvre the ball all around the court, play with variety [and] play with shape".
'It's taken us, Casey and I have been chatting, taken us a few minutes to try and process and think, really think about what actually happened there, ' Smith said afterwards.
Muchova had not dropped a set in the tournament, but that changed against Barty, who worked break points on the Czech's opening serve and converted the second with a forehand victor.
Muchova said she'd then tried to play more aggressively against Barty and utilise more of an all-court game.
Barty became increasingly frustrated throughout the second and third sets, as her opponent raised her game and barely gave her an inch after the first set.