Madison Keys stunned second seed Iga Swiatek 5-7 6-1 7-6(8) in a thriller to reach her first Australian Open final.
American Keys, the 19th seed, will meet double defending champion Aryna Sabalenka in Saturday's decider.
Keys said the personal work she had put in to develop a bolder approach to her game paid dividends on Thursday.
The 29-year-old was a point away from her fourth semi-final exit at Melbourne Park when Swiatek was serving at 6-5 in the deciding set.
Keys turned the match around from there and said her semi-final defeat by Sabalenka in the US Open two years ago taught her how to take her chances and not have regrets.
"I've been doing a lot of personal work with all of that. One of the big things, after I lost to Aryna at the US Open, I felt like I tried to play safe and I wasn't playing how I wanted to in the big moments. That felt so bad," Keys told reporters.
"I felt like if I can go out and do what I want to do and really just be uncomfortable at times and go for it and play the way I play my best tennis, and I lose, then I can walk away and say, 'Okay, I did my best, she beat me, that's fine'.
"I didn't want to be in the same situation where I looked back and thought 'Man, I should have gone for it.' I didn't want to have any regrets for not really laying it all out there."
Swiatek's defeat meant holder Sabalenka, who is aiming for a 'threepeat', will leave the Australian Open as world number one and Keys expects a tough test in her bid to seal a second win over the Belarusian in their sixth meeting on Saturday.