Swiatek held her own serve and then won the first two points as Noskova served for the match. But the Czech player kept her head, firing an ace to set up match point and sealing the deal.
World number one Iga Swiatek said she had failed to play her “natural” game after her 18-match winning run came to a shuddering halt at the Australian Open on Saturday.
The Polish top seed was beaten 3-6, 6-3, 6-4 in the third round by unseeded Czech teen Linda Noskova — ending her hopes of a first title in Melbourne.
Just three of the top 10 women’s seeds remain in the draw in Melbourne at the end of the first week.
Swiatek started the tournament with a straight-sets win against former champion Sofia Kenin before staging a fine comeback to defeat 2022 runner-up Danielle Collins.
But she came unstuck against 50th-ranked Noskova despite winning the first set under the lights on Rod Laver Arena.
A crestfallen Swiatek said she felt the match was under control until she was broken in the second set.
“I was rushing it,” she said. “I just wasn’t playing kind of with my intuition and naturally.
“For sure I was more stressed than in other tournaments, especially the first two rounds,” she added.
“But I think some things just didn’t work as they did before, even though I was working the same way. I feel like I did really everything I could in pre-season to improve some stuff that I wanted to.
“Then I came here and I wasn’t playing kind of natural anymore. I don’t know, like my split step was too late sometimes, reaction a little bit slower, some other things.”
Noskova will face Ukrainian 19th seed Elina Svitolina in the last 16 on Monday.
“It was an unbelievable match for me,” said the 19-year-old. “Playing on such a court for the first time, playing with Iga for a second time, I really wanted to win this, so I’m just glad that I did it.
“I know that I have improved a lot in the last year-and-a-half, year. I mean, I just believed my game tonight.
“I just really wanted this win because I didn’t really come to that court with the thought of, like, I have nothing to lose.”
Swiatek, 22, broke in the sixth game and went on to take the first set in 43 minutes.
Both women faced pressure on their serves in a tight second set and fended off break points until the eighth game, when Noskova broke to love to lead 5-3 before serving out.
Swiatek cracked in the third game of the decider, putting herself in deep trouble, but she hit back immediately after speaking with her coaching team on court.
But she came under pressure on her serve again, saving another break point to edge ahead 3-2.
That proved a temporary stay of execution as she netted with a forehand in the seventh game to give Noskova another break for a 4-3 lead and she held serve for 5-3.
Swiatek held her own serve and then won the first two points as Noskova served for the match. But the Czech player kept her head, firing an ace to set up match point and sealing the deal.