Sania Mirza overcame a concentration lapse in the second set to overcome Austria's Sybille Bammer and enter the singles final at the Stanford Classic in California on Saturday.
The Indian ace shocked the eighth seeded Austrian 6-2, 5-7, 6-3 to set up a summit showdown with top seed Anna Chakvetadze of Russia.
Chakvetadze also had to work hard before getting past third seed Daniela Hantuchova of Slovakia 6-7(6), 6-3, 6-2 in the other semi-final.
It was Sania's third big victory this week, having beaten fourth-seeded Patty Schnyder of Switzerland in the quarter-finals and sixth-seeded Tatiana Golovin of France before that.
Sania is also in sight of her third doubles title of the year after she and Shahar Peer of Israel stormed into the final. The third seeded Indo-Israel pair accounted for the unseeded duo of Hsieh Su Wei (Chinese Taipei) and Alla Kudryavtseva (Russia) 6-3, 6-4 in the semi-final.
"It was all about mental strength," Sania told reporters after the two hour and 14 minutes contest.
"It's a great way to start the hard court season. I've had good wins here and I'm hitting the ball well."
Sania began the match sending down her huge forehand and backhand crosscourt returns that left the Austrian standing..
But in the second set, she began to play more conservatively and paid for it. She was broken four times, the last one in the final game, when she committed a forehand error on set point.
In the third set, the Indian broke Bammer to 4-3 when she ripped a forehand down the line.She won the match when she hit a forehand crosscourt winner on her fourth match point.
"I said I have to hang in there and I did," she said.
"At this level when it's 3-3 in the third set, whoever is mentally tougher and comes up with shots at deuce and 40-30 when it matters the most will come out the winner."
Bammer said Sania, who equalled her career-high ranking of 31 by making the final, has the potential to make the top ten.
"She has the fastest forehand on tour," Bammer said. "She can only go forward from here."
By entering the final, Sania, ranked 35th, could equal or surpass her career-high ranking of 31, which she achieved in October 2005, when the rankings are issued on Monday.
Chakvetadze recorded her ninth straight victory in the United States after out-running Hantuchova, who troubled the Russian with some aggressive groundstrokes.
But Chakvetadze began to spot her serve better in the second set and gained control of the match.
"We both played well, but I was more consistent in the last two sets," Chakvetadze told reporters.
"I had so many opportunities. I'm so tired because she made me run a lot. I knew I had to play more aggressive."
Chakvetadze has a 2-0 record against Sania, including her semi-final victory in Cincinnati last week.