Los Angeles - China's Zheng Saisai surprised seventh-seeded Maria Sakkari 7-6 (7/5), 6-2 on Saturday to line up a title clash with second-seeded Aryna Sabalenka at the WTA tournament in San Jose, California.
Unseeded Zheng knocked off her third seeded opponent of the week, after downing eighth-seeded American Danielle Collins and fourth-seeded US teen Amanda Anisimova in a three-set quarter-final marathon on Friday night.
On Sunday, Zheng will be seeking a first WTA singles title when she takes on Sabalenka, the world number 10 who defeated fifth-seeded Croatian Donna Vekic 6-4, 6-3.
Sabalenka, of Belarus, reached her first final since she won the Shenzhen Open in January.
She and Vekic traded six service breaks in the first seven games before Sabalenka pocketed the set.
Sabalenka broke twice more in the second set to capture the match in just under 80 minutes, after the players combined for 14 double faults and 10 service breaks.
"I don't know, I just hit the ball as hard as I could and everything was going in," Sabalenka said of the key to her victory. "Probably was a lucky day for me."