Chinese's top player Zheng Qinwen battled into the Huafa Technology WTA Elite Trophy Zhuhai final by holding off compatriot Zhu Lin 7-5, 4-6, 6-1 on Saturday.
In the all-Chinese matchup on their home soil, the World No.19 Zheng needed 3 hours and 19 minutes to tough out the win over 37th-ranked Zhu.
Photo gallery: Marathon Marvels 2023: All this year's three-hour matches
No.7 seed Zheng has now won eight matches in a row, which includes her title run at WTA 500 Zhengzhou earlier this month.
Beatriz Haddad Maia will be Zheng's opponent in Sunday's championship match. No.8 seed Haddad Maia of Brazil eased past No.6 seed Daria Kasatkina 6-4, 6-1, reaching her first final of the year in the process.
The final will be the first meeting between Haddad Maia and Zheng, both of whom have reached career-high rankings during 2023.
In the evening semifinal, the Zhuhai crowds were treated to a meeting between two of China's top three players in the WTA singles rankings. It was a repeat of the gold medal match at the Asian Games last month, which Zheng won 6-2, 6-4.
The winner of Saturday's rematch was guaranteed to become only the second Chinese player to reach the Zhuhai final. Wang Qiang finished runner-up to Ashleigh Barty in Zhuhai in 2018.
The marathon tone was set in the opening frame, which Zheng won in 80 minutes. That set included an 18-minute service hold by Zheng for 4-3 where she saved six break points. Zheng also had to save two set points at 5-4 before squeaking out the one-set lead.
Zhu countered by winning the 70-minute second set, during which Zheng had two visits from the physio. In the second set, the pair had 13 winners apiece, but Zhu had five fewer unforced errors than Zheng.
Zheng got a second wind in the final set, while Zhu's unforced error tally rose. Zheng found superb serves when she needed them most, firing two of her 12 aces in a hold for 3-0.
Later, a forehand winner on the baseline gave Zheng a love break for 5-1, and she saved two break points while serving out the win in the following game.
In Saturday's opening semifinal, Haddad Maia took 1 hour and 33 minutes to defeat 17th-ranked Kasatkina for the second time in their two meetings. Haddad Maia also beat Kasatkina in straight sets this year in Doha.
Haddad Maia, who reached her first Grand Slam semifinal at this year's Roland Garros, was impenetrable on serve against Kasatkina on Saturday. The Brazilian won 80 percent of her first-service points and never faced a break point in their showdown.
Coming into this week, Haddad Maia had lost her last four matches against Top 20 opposition, but she has registered three Top 20 wins in a row in Zhuhai, having already beaten Madison Keys and Caroline Garcia in round-robin play before her victory over Kasatkina.
Haddad Maia maintains a spotless record this week. The Brazilian has yet to drop a set in Zhuhai, including in the doubles event, where she is also into the final alongside partner Veronika Kudermetova.