Karolina Muchova saved a match point to beat Coco Gauff 6-2 1-6 7-6 (12-10) after an epic deciding set tie-break to set up an all-Czech final against compatriot Linda Noskova.
A topsy-turvy first semi-final became a battle of attrition and character as neither player was able to break the other in a tight final set, so a 10-point tie-break was required to separate the pair.
It looked like Muchova was suffering from the sweltering heat as she held her abdominal muscle at the start of the tie-break, but she got the first decisive mini-break and found herself 6-3 up.
However, Gauff won three points in a row then had match point at 9-8 up on her serve, only to get an attempted drop shot all wrong.
"People who don't watch tennis are going to be like, 'why did you do that?' At the end of the day, that's the choice I made," said Gauff.
"Was it the right one in that moment? Maybe not. But then also, if I make it, everyone's going to say how clutch of a shot that was."
Muchova then had match point but Gauff produced an outstanding passing forehand winner to save the match, only for Muchova to win the next two points with aggressive hitting to reach her second Grand Slam final.
"Honestly it was such a big fight. A rollercoaster, up and down. In 10 seconds you had match point and then match point against you. There was no time to think," said a relieved Muchova.
"It was very nerve-racking, I don't know what I'm saying. I'm shaking and trying to sink it in. The atmosphere here was indescribable."
For the third consecutive match, Gauff lost the first set as she made several unforced errors and was punished by Muchova who quickly went 5-1 up.
Gauff had chances of her own to break, including at 0-40 up in the sixth game, but was unable to take them as Muchova kept her composure to win the opening set in 40 minutes.
Gauff proved why she is considered one of the best fighters on the women's tour, though, as she upped her groundstroke speed and broke in the fourth and sixth games, with Muchova seemingly rattled by the change in tempo as she lost five successive games.
The Czech player still had the first break point chances in the deciding set in the fourth game but was unable to take them. It was not until the ninth game at 4-4 when the next chances came as this time Muchova saved two and forced Gauff to serve to stay in the match.
The next two games were shared with little drama, so a final set tie-break was needed and both players produced some outstanding tennis with long rallies and brilliant shot-making.
The pick of the highlights reel was a diving volley from Muchova as she consolidated her early mini-break, then took advantage of Gauff fluffing her only match point chance to seal a memorable triumph.
For the first time since the 2017 US Open, two women from the same nation will play each other in a Grand Slam final as Noskova saw off Ukraine's Marta Kostyuk 6-4 6-4.
After the thrilling conclusion to the first semi-final, it took a while for things to heat up with Noskova only earning the first break point chance at 3-2. She was unable to take it.
There were no more breaks until a poor Kostyuk service game when serving to stay in the set was punished by Noskova, who forced errors from her opponent as the set ended in a double fault.
It looked like Noskova was going to run away with the match when she broke in the fourth game of the second set to go 3-1 up but Kostyuk broke back as the crowd urged her on.
Similarly to the first set, Noskova broke in the 10th game to complete a well-deserved win and ensure a first appearance in a major final.
"I tried to be as patient as possible and be cool. Somehow I hit the last point. For me, it's always just to focus on myself and my game," said Noskova.
"When I play my best, I know I can play with the best players in the world and get a great result, which is now a final of a Grand Slam! I'm still in shock I had a chance in my life to play here and get a win. I enjoyed it so much."
