Coco Gauff and Aryna Sabalenka will meet in a rematch of the US Open final on Thursday for a place in the Australian Open trophy decider.
While seeds have fallen around them, Gauff and Sabalenka have made it through to the last four for what feels like a de facto final.
Fourth seed Gauff survived her first test of the tournament, needing three hours and eight minutes to defeat unseeded Ukrainian Marta Kostyuk 7-6 (6) 6-7 (3) 6-2.
Defending champion Sabalenka, though, continued her record of not having dropped more than three games in a set with a swift 6-2 6-3 win against ninth seed Barbora Krejcikova.
The start of the night session was delayed by more than two hours because of long matches in the day, but that did not affect Sabalenka, who said: “I think it was really a great match today, I think I played really great tennis and I hope I can keep playing that way or even better.”
The second seed revealed the players had been asked whether they wanted to move the match to another court but opted to stay on Rod Laver Arena.
Sabalenka lifted her first slam trophy here last year and has been the most consistent female player on the big stage, reaching at least the semi-finals at every major since.
She was favourite to win another title in New York but Gauff turned the tables after losing the first set to claim a 2-6 6-3 6-2 triumph and lift her first slam trophy.
The 19-year-old American is through to the last four here for the first time, but it was a real struggle, with Gauff and Kostyuk committing 107 unforced errors between them.
Gauff trailed 5-1 in the opening set before fighting back to win it, saving two set points.
She served for the match at 5-3 in the second set but now it was Kostyuk’s turn to surge back, and it was not until the third set that Gauff took control of the match, opening up a 5-0 lead.
The teenager is the youngest American to reach the women’s semi-finals in Melbourne since Mary Joe Fernandez back in 1991, and she is two wins away from making it back-to-back slam titles.
“It was a fight,” said Gauff. “I think today was definitely a C game, so I didn’t play my best tennis, but I’m really proud that I was able to get through today’s match. Hopefully got the bad match out of the way and I can play even better.”
“I’m very proud of myself. I won for myself today, and I think it’s the most important thing. It’s just the beginning of the season. I’m looking forward for what’s ahead.”
Kostyuk and countrywoman Dayana Yastremska both made the last eight – Yastremska may yet go further – while Elina Svitolina reached the fourth round, and all have used the opportunity to highlight the ongoing plight of Ukraine.
“I think the girls did really well,” said Kostyuk. “I hope we will be able to succeed in most of the tournaments, especially the big ones where there is a lot of media. I think people should be reminded.
“I was texting with some people from Kyiv. I said, ‘How is it? How are you guys?’ They said, ‘Well, we were looking between your score and where the missiles are flying’. So it’s still there. My parents are still there. My sister is still there.”