Serena Williams and Simona Halep booked a blockbuster date with dominant round-three wins on Saturday, while Naomi Osaka and Elina Svitolina battled their way through.
It was a classy display by Williams in her 6-2 6-1 hammering of Ukrainian teenager Dayana Yastremska on Rod Laver Arena.
Halep then took centre stage in the evening session, clinically dispatching of Williams' sister Venus 6-2 6-3 to set up the match tennis fans the world over hoped for when the draw was made.
There were no major upsets in the women's draw on day six, but Osaka and Svitolina had to dig deep into their reserves.
SERENA SHOWS SOFT SIDE
Yastremska was not even born when Serena won the first of her 23 grand slams at the 1999 US Open, but experience prevailed over youth.
The emotion of defeat was plain to see on the 18-year-old's face after a performance in which she showed plenty of guts.
And Williams consoled her opponent at the net, saying: "You did amazing. You did so well. You did amazing. Don't cry. You did really well!"
HALEP HITTING FORM
World number one Halep needed three sets in her opening two victories, but veteran Venus was blown away by the Romanian on Margaret Court Arena.
Halep, runner-up in Melbourne a year ago, was aided by 33 unforced Williams errors, and she recognises Serena may not be so giving.
"I have just to enjoy, and to give my best," she said. "I actually have nothing to lose – I play against a great champion. It's going to be a bigger challenge, but I'm ready to face it."
NAOMI DOESN'T THROW IN THE TOWEL
There was a comedy moment at the end of Osaka's match against Hsieh Su-wei when trying to gift a memento to the crowd.
But while the fourth seed literally could not throw the towel to the eager spectators, she also did not throw it in metaphorically in her comeback 5-7 6-4 6-1 triumph. She now meets Anastasija Sevastova following the Latvian's straight-sets win over Wang Qiang.
Sixth seed Svitolina had to show similar grit to defeat Zhang Shuai 4-6 6-4 7-5, but Garbine Muguruza had it slightly easier in a 7-6 (7-5) 6-2 beating of Timea Bacsinszky.
Completing the action, Karolina Pliskova (7) and Madison Keys (17) overcame Camila Giorgi and Elise Mertens (12) respectively.