France's Amelie Mauresmo shocked world number one Justine Henin-Hardenne 6-7, 7-5, 6-3 in the semi-finals of the Amelia Island championship on Saturday.
Third seed Mauresmo will face fourth seeded Lindsay Davenport in Sunday's final, after the American beat Russian Nadia Petrova 3-6, 6-4, 6-1 in Saturday's other semi-final.
After a slow start, Henin-Hardenne burst into life by taking the first set tiebreaker 7-4 after 63 minutes and establishing an early lead in the second.
But after the pair had exchanged two breaks of serve, Mauresmo secured the crucial third break to level the match and force a decider.
Belgian Henin-Hardenne, who hit 52 unforced errors overall, failed to create one break point opportunity in the third, allowing Mauresmo to take charge.
She closed out the compelling contest in two hours, 45 minutes.
Seventh-seeded Petrova had knocked out Serena Williams in the quarter-finals on Friday and was hoping to progress to her first ever WTA Tour singles title.
At 6-3, 2-1 with a break against Davenport, the 21-year-old was in control against her error-prone opponent.
However, from 4-2 down in the second, Davenport reeled off seven straight games to level at one set apiece before forging a 3-0 lead in the third.
Petrova's challenge subsided in the decider, winning just 10 points as Davenport won in one hour, 44 minutes.