Three-time major winner Iga Świątek will have to wait another year before she gets the chance to add the Australian Open title to her collection, after falling to Elena Rybakina in straight sets.
Wimbledon champion Rybakina, seeded 22 at Melbourne Park, won 6-4, 6-4 against the Polish world number one to move through to the quarterfinals.
The Russian-born Kazakh will play 17th-seeded Jeļena Ostapenko in the last eight.
Latvian Ostapenko, who won the 2017 French Open, caused un upset with a 7-5, 6-3 victory over seventh-seeded American Coco Gauff in the last 16.
In a later fourth-round match, US third seed Jessica Pegula did not drop a set in defeating Czech 2021 French Open champion Barbora Krejčíková 7-5, 6-2 to make the quarterfinals at Melbourne Park for the third year in a row.
Świątek was the hot favourite to claim her first Melbourne Park title and fourth major crown but had no answers to the big-serving Rybakina on Rod Laver Arena.
Rybakina had never gone further than the Australian Open's third round before this year but showed impressive poise when it mattered, including winning the second set after trailing 3-0.
In reaching the quarterfinals, Rybakina also snapped defending French and US Open champion Świątek's 10-match winning run at the majors.
"It was a really tough match and I really respect Iga because of the streak she had at the grand slams," Rybakina said in her on-court interview.
"She's a young player and she plays really well.
"Today I was serving really good, just struggling on one side but I think in the important moments I played really well, so it made a big difference.
"I'm nervous every time I go on the court, like everybody. But I'm calm always.
"It's a big win and I'm just happy to get to another round."
Rybakina got off to the perfect start when she broke Świątek's serve in the first game.
She teed up three set points and coolly dispatched an ace to claim the opening set.
Świątek fought back immediately in the second set, breaking Rybakina to race out to a 3-0 lead.
But Rybakina would not go away and was able to get the set back on serve.
She earned three break points at 4-4 and converted the third, before coolly serving out the match.
Rybakina's world ranking of 25 is somewhat deceptive as she did not receive any ranking points for her Wimbledon triumph last year.
The WTA and ATP withheld all points at Wimbledon after the All England Club banned players from Russia and Belarus because of the invasion of Ukraine.
It is the third time Świątek, last year's semifinalist, has departed Melbourne Park in the fourth round.
Rybakina's world ranking of 25 is somewhat deceptive as she did not receive any ranking points for her Wimbledon triumph last year.
The WTA and ATP withheld all points at Wimbledon after the All England Club banned players from Russia and Belarus because of the invasion of Ukraine.
Ostapenko closed out victory over Gauff in impressive style to reach the quarterfinals at a major for the first time since her 2018 Wimbledon semifinal appearance.
"I really had nothing to lose so I just went there and tried to show my best and fight for every point and make it hard for her and I'm really happy with the win," Ostapenko said.
"At the end I think I kept her under so much pressure and it brought me a win."
AAP/ABC
