Caroline Garcia rallied from a set down to beat Daria Kasatkina 4-6, 6-1, 7-6 (7/5) on Saturday in a winner-take-all clash that sent the French player into the WTA Finals knockout phase.
The clash for the last semi-final berth was tense and action-packed, Garcia shaking off the frustration of the first set then holding on in the tightly contested third to line up a meeting with fifth-ranked Greek Maria Sakkari.
Round robin play concluded later Saturday with world number one Iga Swiatek, already assured of her semi-final berth, taking on American teenager Coco Gauff, who was eliminated from semi-final contention on Thursday.
Garcia, ranked sixth, became the first player in 30 attempts this season to beat Kasatkina after dropping the first set.
After rolling through the second set, she had a chance to break in the 13-minute ninth game of the third, but Kasatkina saved six break points to hold as they went to a tiebreaker.
Garcia gave herself two match points with a gutsy rally, sending Kasatkina wide with a swinging forehand volley then firing a backhand volley cross-court.
Kasatkina saved one match point, but dropped a volley into the net on the next.
"I tried to keep being very positive, tried to go for my game style being very aggressive," Garcia told Tennis Channel.
"Every match we say you have to give it all and no regrets, go for it and it's always true, but in this tournament even more -- it's the last one (of the season).
"We did know that the winner was going through in the semi-final. It's a big achievement so I really tried to give everything I had."
Garcia takes a 2-0 career lead over Sakkari into Sunday's semi-final, including a victory at Cincinnati this year on route to the title.
Swiatek, winner of the French Open and US Open this year, will face seventh-ranked Aryna Sabalenka in the semis at Dickies Arena in Fort Worth.
The event was moved to Texas due to continuing pandemic-related issues with the Chinese city of Shenzhen, which was initially due to host, as well as the WTA's dispute with China over the status of player Peng Shuai.