Second-seeded Caroline Wozniacki downed good friend Agnieszka Radwanska 6-2, 6-3 on Friday to book a final showdown with former world number one Jelena Jankovic at the BNP Paribas Open.
By reaching the final, Wozniacki is projected to reach a career-high number two in the world next week, up two spots from her current number four.
"Right now I'm just happy about my result here," the 19-year-old Dane said. "I'm thinking about this tournament, and that's the most important thing for me right now."
After the two traded breaks in the fifth and sixth games of the second set, Wozniacki gained the upper hand for good with a break in the seventh game courtesy of a forehand cross-court winner.
She saved a break point in the next game, then closed it out with one more service break as Radwanska hooked a forehand wide on match point.
"I thought that I played a really good match," Wozniacki said. "I played consistent and tried to be aggressive, but there was a fine line between playing over aggressively and too passively.
"You know, we know each other so well," added Wozniacki, who exchanged a big hug with her friend at the net after the match.
"We know each other's strengths and weaknesses. Agnieszka is a great fighter. She doesn't give up. I knew that I had to fight till the last point to win this match."
The final will be the first of the year for both Wozniacki and Jankovic.
"I feel great. I'm so happy to be in the finals for the first time here," said Jankovic, whose previous best performance in Indian Wells was a semi-final loss to eventual champion Ana Ivanovic in 2008.
"I haven't been doing well the last couple tournaments," added Jankovic, who fell in the third round at both the Australian Open and the Dubai Open last month, and bowed out in the first round at Sydney and Monterrey.
"I thought the key to today's match was my return," the 25-year-old Serbian said. "Samantha has an unbelievable serve, one of the best serves in the women's game, and I was able to return a lot of her first serves.
"I think she felt uncomfortable, because she really relies on that shot. That's her best weapon."
Stosur, the eighth seed who came into the tournament ranked a career-high 11th in the world, is projected to break into the top 10 on Monday by virtue of reaching the semis.
She saved one match point on her own serve in the ninth game of the second set, and held to make Jankovic serve it out.
Jankovic had to fend off two break points, but finished it off with a serve that Stosur could only swipe out.
"It was a great week, but today I definitely didn't play anywhere close to as well as what I can," Stosur said.