The world No. 1 took the first set on Rod Laver Arena before Nosková mounted a stunning comeback to win 3-6 6-3 6-4, claiming the biggest victory of her young career.
Poland’s Świątek looked in control of the third-round contest when it was on serve at 4-3 in the second set, but Nosková, ranked No. 50 in the world, secured the break to love with a forehand winner.
The pair traded breaks at the start of the deciding set before Nosková gained the upper hand at 3-3, breaking Świątek’s serve and seeing out the rest of the match.
According to Opta, it’s the first time that a teenager has defeated the world No. 1 at the Australian Open since Amélie Mauresmo did so against Lindsay Davenport in 1999.
It marked only Świątek’s second defeat to a player younger than her at tour level, and snapped her 18-match winning streak that had stretched back to last September.
“I’m speechless, obviously,” Nosková said in her on-court interview after the match. “I knew it was going to be an amazing match with the world No.1. I definitely didn’t think that it would end up like this. I’m just really glad to get through this round.”
This is Nosková’s first appearance in the main draw of the Australian Open and the first time that she has reached the fourth round of a grand slam, where she will face either Ukraine’s Elina Svitolina.
Her victory also means that there is only one former grand slam champion in the top half of the women’s draw at this year’s tournament, Belarus’ Victoria Azarenka.
After starting the year with a run to the semifinals of the Brisbane International, Nosková defeated compatriot Marie Bouzková and American McCartney Kessler in the first two rounds at Melbourne Park.
Against Świątek, she hit 10 aces, including a crucial one in the final game of the match, and 35 winners.
“I was a little shaking [while serving for the match],” said Nosková. “Obviously I didn’t hit two first serves which wasn’t the best start for me but I pulled out an ace and it’s easier like that. It’s tough sometimes to bring it.”
As for Świątek, who struggled with the consistency of her forehand towards the end of the match, she has now only progressed beyond the fourth round of the Australian Open once in six attempts.
“I felt like I had everything under control, but I think she just went all in without any pressure,” the 22-year-old told reporters.
“She probably knew that she has nothing to lose. Maybe I should have done that when I had break points in previous games, but I wanted kind of to be the solid version of myself.”
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