Madison Keys of the U.S. celebrates after defeating Iga Swiatek of Poland in their semifinal match at the Australian Open tennis championship in Melbourne, Australia. (AP)

MELBOURNE, Australia, Jan 23, (AP): When Madison Keys finally finished off her 5-7, 6-1, 7-6 (10-8) upset of No. 2 Iga Swiatek in a high-intensity, high-quality Australian Open semifinal on 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'd 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 U.S. 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 (yes, Madison, she was, serving at 6-5, 40-30, but missed a backhand into the net, then eventually got broken by double-faulting), sending 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 sure 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.