US Open champion Sloane Stephens will face French Open winner Jelena Ostapenko in the Miami Open final after the American's magnificent semi-final comeback against Victoria Azarenka.
Belarusian Azarenka took the first two games of the second set but Stephens won 10 straight games to turn the tie around and win 3-6 6-2 6-1.
Latvia's Ostapenko progressed later on Thursday with a 7-6 (7-1) 6-3 win over American qualifier Danielle Collins.
The pair meet in the final on Saturday.
Stephens set to break into top 10
Thursday's last-four match was the second time world number 12 Stephens has defeated Belarusian wildcard Azarenka this month, having won in straight sets in the second round at Indian Wells.
Three-time Miami Open winner Azarenka, 28, comfortably won the first set but hit four double faults in the second as the American started to dominate.
Stephens will now move into the top 10 for the first time next week, while two-time Australian Open champion Azarenka - who was playing only her fourth tournament since maternity leave - will climb back into the top 100.
"I knew I had to stay in it. Victoria is a great champion," said Stephens, 25. "I kept battling and I got a little momentum going in the second set.
"Growing up in South Florida, this is so incredible to be in the final.
"I knew I had to focus on my side of the court and be solely focused on myself."
'Mentally stronger' Ostapenko ends Collins' run
Ostapenko, 20, became the youngest finalist in Miami since Azarenka won the title in 2009 when she was aged 19.
She needed just two sets and little under two hours to end the run of 24-year-old Collins, who had already knocked out Venus Williams, Coco Vandeweghe and Monica Puig.
The Latvian's heavy-hitting proved too strong for her opponent, ruthlessly taking her serve four times in the first-set tie-break and then breaking Collins again in the opening game of the second set.
Ostapenko closed out the victory with her first match point and will now climb to world number four following the final.
"I think I'm calmer, and also mentally I'm stronger now," said Ostapenko. "More consistent and more confident and just going for shots sometimes and not afraid to miss it."
Collins, who has earned more prize money in Miami than she had previously won in her whole career, will move into the the world's top 100 for the first time.