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.

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.

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Karolina Muchova of the Czech Republic hits a backhand return to Australia's Ash Barty during their quarterfinal match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoHamish Blair)

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.

Karolina Muchova of the Czech Republic places a bag of ice on her head after defeating Australia's Ash Barty in their quarterfinal match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoHamish Blair)

Early in the second set, Muchova took an injury timeout that lasted nearly 10 minutes. Medical personnel took her pulse and temperature before she left the court, and when the Czech returned, she played much better.

Australia's Ash Barty, left, congratulates Karolina Muchova of the Czech Republic after their quarterfinal match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoAndy Brownbill)

Against Barty, she began moving into the court to hit her groundstrokes earlier. Barty, pushed behind the baseline, became indecisive and erratic.

Karolina Muchova of the Czech Republic hits a backhand return to Australia's Ash Barty during their quarterfinal match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoAndy Brownbill)

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Australia's Ash Barty wipes the sweat from her racket during her quarterfinal match against Karolina Muchova of the Czech Republic at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoAndy Brownbill)

Australia's Ash Barty wipes the sweat from her racket during her quarterfinal match against Karolina Muchova of the Czech Republic at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoAndy Brownbill)

Muchova played poorly at the start of her second major quarterfinal, and Barty raced to a 5-0 lead while losing only six points. After nine games, Muchova had one winner and 18 unforced errors.

Karolina Muchova of the Czech Republic hits a backhand return to Australia's Ash Barty during their quarterfinal match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoHamish Blair)

Karolina Muchova of the Czech Republic hits a backhand return to Australia's Ash Barty during their quarterfinal match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoHamish Blair)

Early in the second set, Muchova took an injury timeout that lasted nearly 10 minutes. Medical personnel took her pulse and temperature before she left the court, and when the Czech returned, she played much better.

Muchova’s opponent Thursday will be the winner of the last quarterfinal, an all-American matchup between No. 22-seeded Jennifer Brady and unseeded Jessica Pegula.

Comebacks have been a staple in the tournament for Muchova, who rallied in earlier matches to win sets after trailing 5-0 and 4-0.

Karolina Muchova of the Czech Republic places a bag of ice on her head after defeating Australia's Ash Barty in their quarterfinal match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoHamish Blair)

Karolina Muchova of the Czech Republic places a bag of ice on her head after defeating Australia's Ash Barty in their quarterfinal match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoHamish Blair)

Against Barty, she began moving into the court to hit her groundstrokes earlier. Barty, pushed behind the baseline, became indecisive and erratic.

During one stretch Muchova won eight of nine games. Barty finished with 37 unforced errors and lost serve four times in the final two sets.

Muchova's only other victory over a top-five was against No. 3 Karolina Pliskova at Wimbledon in 2019.

Australia's Ash Barty, left, congratulates Karolina Muchova of the Czech Republic after their quarterfinal match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoAndy Brownbill)

Australia's Ash Barty, left, congratulates Karolina Muchova of the Czech Republic after their quarterfinal match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoAndy Brownbill)

More AP tennis: https://apnews.com/hub/tennis and https://twitter.com/AP_Sports

Karolina Muchova of the Czech Republic hits a backhand return to Australia's Ash Barty during their quarterfinal match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoAndy Brownbill)

Karolina Muchova of the Czech Republic hits a backhand return to Australia's Ash Barty during their quarterfinal match at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoAndy Brownbill)

Australia's Ash Barty wipes the sweat from her racket during her quarterfinal match against Karolina Muchova of the Czech Republic at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoAndy Brownbill)

Australia's Ash Barty wipes the sweat from her racket during her quarterfinal match against Karolina Muchova of the Czech Republic at the Australian Open tennis championship in Melbourne, Australia, Wednesday, Feb. 17, 2021.(AP PhotoAndy Brownbill)