When Madison Keys finally finished off her 5-7, 6-1, 7-6 (8) upset of No. 2 Iga Swiatek in a high-intensity, high-quality Australian Open semifinal Thursday night, saving a match point along the way, the 29-year-old American crouched on the court and placed a hand on her white hat.

She had a hard time believing it all. The comeback. What Keys called an "extra dramatic finish." The victory over five-time Grand Slam champion Swiatek, who had been on the most dominant run at Melbourne Park in a dozen years. And now the chance to play in a Grand Slam final for a second time, eight years after being the US Open runner-up.

"I'm still trying to catch up to everything that's happening," said the 19th-seeded Keys, who will face No. 1 Aryna Sabalenka on Saturday for the trophy. "I felt like I was just fighting to stay in it. ... It was so up and down and so many big points."

Just to be sure, Keys asked whether Swiatek was, indeed, one point from victory. She was, serving at 6-5, 40-30, before missing a backhand into the net then getting broken by double-faulting to send the contest to a first-to-10, win-by-two tiebreaker.

"I felt like I blacked out there at some point," Keys said, "and was out there running around."

Whatever she was doing, it worked in the end. Keys claimed more games in the semifinal than the 14 total that Swiatek dropped in her five previous matches over the past two weeks.

Sabalenka beat good friend Paula Badosa 6-4, 6-2 earlier Thursday. Sabalenka, a 26-year-old from Belarus, won the Australian Open the past two years and can become the first woman since 1999 to complete a three-peat.

"If she plays like this," the 11th-seeded Badosa said about Sabalenka, "I mean, we can already give her the trophy."

The last woman to reach three finals in a row at the year's first Grand Slam tournament was Serena Williams, who won two from 2015 to 2017. Martina Hingis was the most recent woman with a three-peat, doing it from 1997 to 1999.

Swiatek had not lost a service game since the first round but was broken three times by Keys in the first set alone and eight times in all.

That included each of Swiatek's first two times serving, making clear from the get-go this would not be her usual sort of day. While Swiatek did eke out the opening set, she was overwhelmed in the second, trailing 5-0 before getting a game.

This was the big-hitting Keys at her best. She turns 30 next month, and at the suggestion of her coach Bjorn Fratangelo, who's a former player as well as her husband, she decided to try a new racket this season, an effort both to help her with generating easy power but also to relieve some strain on her right shoulder.

It's certainly paid immediate dividends. Keys is on an 11-match winning streak, including taking the title at a tuneup event in Adelaide.

She was good enough to get through this one, which was as tight as can be down the stretch.

"At the end, I feel like we were both kind of battling some nerves. ... It just became who can get that final point and who can be a little bit better than the other one," Keys said. "And I'm happy it was me."

Keys' victory made her the first woman to come from a set down to win an Australian Open semifinal since Venus Williams in 2017; Williams defeated CoCo Vandeweghe before losing to her sister Serena in the final.

The Associated Press contributed to this report.