Zhang, seeded third, defeated No. 2-seed Yanina Wickmayer 1-6, 6-4, 6-4. After a first set in which Zhang won just 10 points -- about one-quarter of the points -- and didn't manage a break point, Zhang piled up three breaks in the second set and two more in the third.
Morita, the No. 4 seed, advanced over qualifier Jarmila Gajdosova 7-6 (8-6), 6-2 by winning more the 60 percent of the points on serve and nearly half -- 38-of-79 -- when Gajdosova served.
After the tight first set, Morita had three second-set breaks in earning her first WTA finals berth in more than five years. Sunday will mark her third championship match. She lost tries in 2007 and 2008.
Zhang appeared in her first WTA title match in September and won the Guangzhou International Women's Open, also in China.
Morita owns a 2-1 career edge over Zhang, with all the matches coming in 2011.
Sunday's tournament champion will take home $20,000 with the runner-up earning $11,000. Wickmayer and Gajdosova each collected $6,000 as semifinalists.