Wins over Jabeur, Azarenka and Daria Kasatkina on the WTA Tour last year drew attention to Noskova, but this is by far the biggest win of her young career.
She is the first teenager to beat a world number one at a Grand Slam since Petra Kvitova overcame Dinara Safina at the 2009 US Open.
After two tight sets, Noskova broke serve for 2-1 in the decider, saw a refocused Swiatek break back before then regaining the decisive break at 4-3.
The four-time Grand Slam champion applied pressure at 30-30 when Noskova served for the match but the Czech fired down an ace before a big first serve helped wrap up victory.
For Swiatek, this is her earliest exit at a Grand Slam since 2022, although it continues her mixed fortunes in Melbourne where one semi-final appearance is her only run beyond the fourth round in six attempts.
This year she almost lost in the second round, having to mount a comeback from 4-1 behind in the third set against Danielle Collins, and after Saturday’s defeat she admitted she was “more stressed” this week than in other tournaments on tour.
“I feel like I did everything I could in pre-season to improve some stuff that I wanted to,” she said.
“Then I came here and I wasn’t playing kind of natural any more [and] reactions a little bit slower.”
She said a fourth-round defeat last year “took her off balance” but this year she wants to “back to work”.
“I know I’m going to have plenty of chances during the season to show my game,” she added.