Camila Giorgi claimed a thrilling semi-final win over Wang Qiang to reach the Bronx Open decider, while Magda Linette also progressed on Friday.
Giorgi saved four match points to edge top seed Wang 4-6 6-4 7-6 (8-6) after two hours, 39 minutes in New York City.
The Italian came from a break down three times in the third set, saving her first match point in the 10th game.
Giorgi squandered a match point of her own in the 12th game before coming from 6-3 down in the tie-break to reach an eighth WTA Tour final.
She will face qualifier Linette, who upset fifth seed Katerina Siniakova 7-6 (7-3) 6-2 in their semi-final.
Linette is into her second WTA Tour decider and lost to Giorgi in three sets when they last met in 2015.