Konta, the world No. 10, would have been eyeing up more silverware as the highest seed left in the tournament but she did not count on a stunning performance from the world No. 52 who earned a 1-6, 6-4, 6-4 win.
Such a result barely seemed possible after Konta breezed to the first set in just 22 minutes, dropping only 13 points.
A solitary break in the second set was enough to level it up, but her plight looked perilous in the decider as Konta had one foot in her third WTA final leading 4-2.
But the 20-year-old showed her mettle by reeling off four successive games, including a love service hold, to clinch her first final on the tour where she will meet Alison Riske.
American No. 8 seed, Riske, beat Camila Giorgi in straight sets, 6-3, 6-3 to put herself one win away from her second WTA title.