Garcia's dream debut will continue on Saturday with a semi-final against an evergreen Venus Williams
Caroline Garcia produced a stunning comeback to overcome Caroline Wozniacki 0-6, 6-3, 7-5 and advance to the last four at WTA Finals on Friday, the Frenchwoman topping the Red Group after top seed Simona Halep lost later in the day.
Elina Svitolina knew she was out of the running for a semi-final berth following Garcia's win in the day's opening round-robin match but that did not prevent the Ukrainian from producing her best display of the week.
Svitolina, who had lost her two previous Red Group encounters, blasted her way to a 6-3, 6-4 victory over Halep, ending both their campaigns.
That result meant Garcia, the last woman to qualify for Singapore, progressed along with Denmark's Wozniacki, who was assured of a semi-final berth on Wednesday after easily winning her opening two pool matches.
Garcia's dream debut will continue on Saturday with a semi-final against an evergreen Venus Williams, while Woznaicki takes on White Group winner Karolina Pliskova, who can replace Halep as world number one if she wins the tournament on Sunday.
Friday's first match started as expected with Wozniacki, whose serve had been impenetrable all week, opening with a love hold before the Dane attacked a lethargic Garcia, who coughed up a couple of forehand errors to gift her an early break.
Wozniacki had recorded two 'bagels' in the wins over Svitolina and Halep, and the 27-year-old chalked up a third 6-0 set in as many matches after just 22 minutes of dominant action.
However, Garcia regrouped to finally get a foothold in the match in the second set, deploying her devastating forehand to full effect to fashion three breaks of serve as Wozniacki's levels dipped.
As the match drifted into a decider, the Dane rediscovered her range. She began to assert pressure on Garcia's weaker backhand side and was rewarded with an early break.
But the Frenchwoman was fighting tooth and nail to stay in the tournament and covered every inch of the court to tie it up at 5-5 on her third breakpoint as Wozniacki attempted to serve for the match in a thrilling 10th game.
Garcia once again dug deep to recover from 0-40 down in the 11th game edge ahead in the decider and the Frenchwoman sealed a memorable victory on her second match point when a Wozniacki backhand sailed long.
"The first set she was playing amazing and I was a little bit down, not believing enough and she gave me nothing," Garcia, who has now won 13 of her last 14 matches, said in a courtside interview.
"Then at the start of the second set, I felt I had nothing to lose and increased my intensity and was able to find my rhythm and finish well."
Despite going into the contest knowing she can go no further in the tournament, Svitolina came out motivated and broke Halep at the first opportunity, the Ukrainian rewarded for a far more aggressive approach than she employed in her previous ties.
The world number four kept her nose in front with her positive play as Halep struggled to find any sort of rhythm and Svitolina carried the momentum of the early break all the way to a one-set lead after 32 minutes.
Locked at 3-3 in the second set, Svitolina continued to play with the freedom that was missing in her opening losses and more sloppy play from Halep enabled the Ukrainian to edge ahead and she sealed victory when the Romanian found the net on the second match point.