RIYADH, Saudi Arabia -- World No.3 Coco Gauff upset No.1 Aryna Sabalenka in the semifinals of the WTA Finals Riyadh presented by PIF to advance to Saturday's championship match. The 20-year-old American handed Sabalenka her second consecutive loss in Riyadh, winning 7-6(4), 6-3 to become the third player since 2010 to score wins over both the World No.1 and No.2 at the WTA Finals.

With the win, Gauff became the youngest player to make the championship match at the WTA Finals since Caroline Wozniacki in 2010 and the youngest to beat No.1 at the season-ending championships since Maria Sharapova defeated Lindsay Davenport in 2004. She is now a win away from becoming the youngest WTA Finals champion since Sharapova's 2004 title run.

Gauff will face Olympic champion Zheng Qinwen for the title Saturday. Zheng advanced to the final after defeating Wimbledon champion Barbora Krejcikova in the first semifinal. Saturday's winner will take home a record $4,805,000, the largest prize money check in the history of women's professional tennis.

WTA Finals Riyadh: Scores | Schedule | Standings

Friday's semifinal pitted the two winningest hard-court players against each other, with Sabalenka leading the tour with 40 wins on the surface and Gauff just behind her with 33. Gauff and Sabalenka split their eight previous meetings, but Sabalenka held the edge this season, besting the American in the semifinals of the Australian Open and Wuhan Open.

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Despite the two losses, Gauff came into the semifinals full of confidence. In Wuhan, she took Sabalenka to three sets despite striking a career-high 21 double faults. Sabalenka edged her out in the end, winning 1-6, 6-4, 6-4, but the 20-year-old left knowing the result would have been different if she minimized her serving errors.

That's precisely what she did to avenge the loss on Friday. Gauff broke her 4-4 deadlock with Sabalenka with a solid display from the service line and courageous work from the baseline. Gauff confidently swung through her forehand to beat Sabalenka with pace, while using her speed to extend points and test the top seed's rally tolerance.

On this day, Sabalenka struggled to meet the challenge. Gauff outpaced Sabalenka in the winner column in the tight opening set, hitting 11 to six. Sabalenka struck 18 forehand unforced errors. Both players broke twice in the opening set, but Gauff was able to maintain more sustained pressure, generating six break points to Sabalenka's three.

"I knew I had worked hard on my serve since [Wuhan]," Gauff said. "That was 21 free points that I gave. I knew if I could cut that in half, I would give myself a better chance and obviously I did well over that today.

"Obviously she's a great player, but I just felt like if I can just play well and serve well, I had a good chance. And once, you know, I stepped on the court and realized I was feeling my serve, I just kind of had that belief that I can win."

With Sabalenka serving at 6-5, Gauff broke her to force the tiebreak, the American raced to a 4-0 lead. Sabalenka charged back to 6-5 but struck her final unforced error of the set to hand Gauff the set.

"Honestly, I have to say she just got lucky in those couple of points at the end of the first set," Sabalenka said, "and I kind of got distracted and let the game go. And then it was too late to come back in the tiebreak, and I lost the first set.

"I was rushing and and not really adjusting to the ball quite well that I did in the first two matches. So I have to say that this match is just full of missed opportunities from my side."

Gauff took that momentum into the second set, breaking open the match to lead 4-1 before closing out her first win over a reigning No.1 since beating Swiatek en route to the Cincinnati title last summer. She is the youngest player to defeat No.1 and No.2 at a single event since Maria Sharapova at the 2006 US Open.

Despite the loss, Sabalenka will still finish her 2024 campaign as the year-end World No.1. The reigning Australian Open and US Open champion came into Riyadh looking to hold off No.2 Iga Swiatek to finish the year atop the rankings for the first time in her career. Sabalenka secured the top spot after Gauff defeated Swiatek in group play earlier in the week.