Garbine Muguruza reached her first Australian Open final after beating fourth seed Simona Halep 7-6(8) 7-5 on Rod Laver Arena.
Muguruza edged a dramatic contest which lasted two hours and five minutes and will face Sofia Kenin, who knocked out Ash Barty in straight sets, in Saturday's final.
The unseeded Spaniard arrived at Melbourne Park with low expectations but will now face American 14th seed Kenin bidding to win her third major title after emerging from a period in the Grand Slam wilderness.
With the temperature nudging a scorching 40 degrees Celsius (104F), Muguruza was dragged into a see-sawing scrap by Halep, a former finalist at Melbourne Park.
Muguruza held her nerve in the first set by taking the third break point in a lengthy tiebreak.
The Spaniard had to break back from 5-4 down in the second set and then held firm to claim the win on a second match point when Romanian Halep failed to clear the net on an attempted passing shot.
The 26-year-old Muguruza would not have been on many lists of pre-tournament contenders but the class and fighting spirit that propelled her to the 2016 French Open and 2017 Wimbledon titles has come flooding back in Australia.
"I'm very excited to be in the final," she said in her on-court interview. "But a long way still to go and I have a big match on Saturday.
"I wasn't thinking that I was down. I thought keep going and some point you will have your opportunity.
"I knew facing Simona was going to be a hard match but I hung in there and fought with all the energy I had.
"Luckily I have 48 hours to recover and get ready for the last match. We train all of our career to play on this court and in front of this crowd."