Czech teenager Linda Noskova came from a set down to stun World No.1 Iga Swiatek 3-6, 6-3, 6-4 in the third round of the Australian Open, advancing to the fourth round of a major for the first time.

She will next face No.19 seed Elina Svitolina, who advanced with a 6-3, 6-2 win against Viktorija Golubic in 64 minutes.

The 19-year-old Noskova's 2-hour, 20-minute victory snaps Swiatek's 18-match winning streak dating back to September last year. It marks just the second time that Swiatek has lost to a player younger than her at tour level, following Coco Gauff's victory in the Cincinnati semifinals last year, and only her second loss before the fourth round in her past 14 majors. 

The result is the earliest loss by a No.1 seed at the Australian Open since 1979, when Virginia Ruzici lost to Mary Sawyer in the first round and the first time since the tournament became a 128-player draw in 1988 that the top seed has not made the fourth round.

"I felt like I had everything under control until she broke me in the second set," Swiatek said afterward. "But, yeah, well, I had couple of chances to break her in second set and I didn't use them. So that's a shame.

"But when she broke me, she was kind of proactive. I wanted to do that as well later in the next games. Sometimes, yeah, I was rushing it. I just wasn't playing kind of with my intuition and naturally."

The 50th-ranked Noskova, who reached two Hologic WTA Tour finals in her 2023 rookie season and who started 2024 with a run to the Brisbane semifinals a fortnight ago, notches her fourth career victory over a Top 10 player. It was her first win at a Grand Slam and first over a reigning World No.1.

The last teenager to defeat the World No.1 at a major was Petra Kvitova, who upset Dinara Safina in the third round of the 2009 US Open at the age of 19. The last teenager to defeat the World No.1 at the Australian Open was Amélie Mauresmo, who defeated Lindsay Davenport in the 1999 semifinals at the age of 19.

Noskova is competing in only her sixth Grand Slam main draw, and first in Melbourne. This time last year, having reached her first career final as a No.104-ranked qualifier in Adelaide, she fell in the first round of Australian Open qualifying to Katherine Sebov. Now, she has leveled her head-to-head against Swiatek at one win apiece, having lost 6-1, 6-4 to the Pole in the Warsaw quarterfinals last July.

How Noskova pulled off the upset: Noshkova had made a name for herself last year with easy natural power, but it was evident in her Brisbane run that she had added to that with improved movement and a confidently executed drop shot. Both were evident from the start of the match, and Noskova was the first player to hold break points as early as the third game.

But Swiatek saved both, then hit back to break Noskova for 4-2 after a four-deuce tussle. She wasted no time in testing Noskova at the start of the second set, finding a screaming backhand return winner to pile on the pressure in the very first game.

Noskova responded to losing a competitive opening set by raising her level, however. She tidied up the elements of her game that had let her down: a ratio of 11 winners to 16 unforced errors in the first set became 15 winners to 12 unforced errors in the second, and her first serve percentage went up from 56% to 68%.

These improvements helped Noskova deliver some clutch plays. She faced a break point at 2-2, and another at 3-3 and found a service winner to save both. Leading 4-3, it was her turn to pounce. She found three brilliant winners, culminating in a forehand return rocket, to break Swiatek for the first time. Noskova didn't blink serving out the set, finding three service winners and one ace to level the match.

By now, Swiatek's forehand was leaking errors; Noskova took advantage of two to break for 2-1. Swiatek found the range on that wing again to break back and seemed to have turned momentum in her favor when she held for 3-2, having saved a break point with a terrific backhand winner down the line.

But at 3-3, another flurry of forehand errors enabled Noskova to break again. This time, she maintained her lead with coolly aggressive play: a pair of backhand winners to hold for 5-3, and another series of unreturnable serves to close out the match from 0-30 down.

Noskova on her improvement: "I know my game. I know that I have improved a lot in the last year and a half. 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.' I took it very seriously.

"A lot of times I have played a Top 10 player, it was -- let's say 100% of the time -- 'I have nothing to lose and I'm just going to go there and try to play my best and we'll see how it goes.' A few times I have beaten a great player, but it was maybe a fluke or something like that, let's say, especially in my head. I didn't go on court with 1000% trust and belief I can win the match. I just played good that day and it went my way.

"I felt like tonight I was actually a little stressed from the morning, which doesn't really happen to me much often. I knew that it means a lot to me."

Noskova on the importance of her serve: "I wanted to work on my serve a lot. Obviously my game is to be aggressive almost all the time, especially at the right times. I just work on that daily just to improve the spots where I hit it.

"When I have such a match like tonight and I'm playing good and I'm feeling good, a lot of points can go my way without even me realizing it, fully knowing if I had planned it or not."

Svitolina returns to Melbourne fourth round

Former World No.3 Svitolina was named 2023's Comeback Player of the Year in last month's WTA awards following her return from maternity leave, and she's bringing that momentum into the new season as well.

The 29-year-old is fresh off a run to the Auckland final and improved her 2024 record to 7-1 after striking 19 winners to beat Golubic for the second time in as many meetings. The result means that Svitolina joins Dayana Yastremska and Marta Kostyuk to make three Ukrainians in the Australian Open last 16, an all-time Grand Slam record.

Svitolina advances to the second week in Melbourne for the fourth time and first since 2021. She is into the second week of a major for the 16th time and will face Noskova for the first time.