Aryna Sabalenka will face impressive 18-year-old American Iva Jovic in the Australian Open quarterfinals, where Carlos Alcaraz aims to join them in his history bid later Sunday.
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After brutal heat nearing 40C disrupted play on Saturday, temperatures eased to a comparatively cool 22C at Melbourne Park as the business end of the tournament started.
Belarusian top seed Sabalenka, a two-time Melbourne champion, opened the day on Rod Laver Arena and saw off the brave challenge of 19-year-old Canadian Victoria Mboko.
Sabalenka won 6-1, 7-6 (7/1) and faces another exciting prospect in Jovic in the last eight.
The 29th-seeded Jovic destroyed unseeded Yulia Putintseva 6-0, 6-1 in just 53 dominant minutes.
"What an incredible player for such a young age," said Sabalenka of the 17th-seeded Canadian Mboko, who has emerged as a serious threat in the past year.
"I feel like I am a kid still! She pushed me really hard today and played incredible tennis."
Sabalenka raced through the second-set tiebreak – the 20th Grand Slam tiebreak in a row she has won – to seal victory.
She has yet to drop a set at the tournament as her title charge ominously gathers pace.
But in Jovic, who only turned 18 last month, she clashes with a player in red-hot form and rising fast, now ranked 27 having been 191 this time last year.
Jovic, who stunned two-time Grand Slam finalist and seventh seed Jasmine Paolini in the third round, said: "I feel great. I'm really glad to get through.
"I said it last year, I hope to be able to play her this year because you definitely want to play the best and see how it goes," she added of Sabalenka.
Third seed Coco Gauff faces Czech 19th seed Karolina Muchova while Ukraine's Elina Svitolina takes on another 18-year-old, Russian Mirra Andreeva, in the other women's round-four matches.
The winners will face each other in the quarterfinals.
GAUFF SEES OFF MUCHOVA TO MAKE AUSTRALIAN OPEN LAST EIGHT
Coco Gauff dropped a set for the second match in a row before clawing her way into a third consecutive Australian Open quarterfinal on Sunday as she zeroes in on a maiden Melbourne title.
The American third seed rolled over seasoned Czech 19th seed Karolina Muchova 6-1, 3-6, 6-3 on Margaret Court Arena, but needed nearly two hours to do so.
She will play either Ukraine's 12th seed Elina Svitolina or 18-year-old Russian eighth seed Mirra Andreeva for a place in the semifinals.
"She definitely elevated her game and I thought sometimes I was a bit passive, but it's really tough to play her," said the 2025 French Open and 2023 US Open champion.
"She plays with so much variety, you never know what you're going to do. I'm really happy to get through this one today."
The 21-year-old Gauff has never gone beyond the last four at Melbourne Park.
Muchova had pedigree, bidding to make an eighth career Grand Slam quarterfinal and she made life difficult after a slow start.
Gauff had a psychological advantage before a ball was hit, winning all four previous encounters and never losing a set, including an easy victory at the United Cup this month.
And she made the best possible start, with back-to-back breaks of Muchova who blasted a slew of unforced errors, racing 4-0 in front.
Gauff's serve has been her Achilles' heel in recent times, but she had few issues with it initially.
Instead, it was Muchova who struggled, winning just 33 per cent her first-serve points in the set.
The Czech player finally held for 1-5 to avoid a dreaded bagel, but it just delayed the inevitable with Gauff taking the set in 30 minutes.
Muchova began with more intent in set two, holding then taking advantage as Gauff's serving yips returned to ease 2-0 ahead.
Gauff broke back but again failed to hold and Muchova took a set off her for the first time in her career.
The crucial moment in the third set came when Muchova spilt a forehand long on serve to give Gauff three break points in game three, with another loose shot from the Czech sealing her fate.
Gauff held serve for 4-1 and safely sealed the win on her fourth match point.