RIYADH, Saudi Arabia — Prodigies tend to reveal themselves quickly.

Coco Gauff was a junior sensation, reached Wimbledon’s fourth-round at the age of 15 and won a Grand Slam singles title while still a teenager.

But the year after winning the US Open has been an adventure for the 20-year-old American, a series of sometimes surprising losses at the Grand Slams and the Olympics. Gauff split with coach Brad Gilbert after she failed to defend her title in New York. Jean-Christophe Faurel and Matt Daly are now part of the team, charged with upgrading Gauff’s serve and forehand.

“I was looking for someone that was going to help me improve for the long term and be committed to that,” Gauff said.

Less than two months later — still very much in the short term — Gauff is the champion of the WTA Finals Riyadh presented by PIF.

She was a 3-6, 6-4, 7-6 (3) thrilling comeback winner Saturday against Zheng Qinwen. It was the first title match at the year-end championship to go the distance in six years, and the run time was 3 hours and 4 minutes, the longest Finals match going to back to 2008.

Gauff is the youngest player to win the WTA Finals since Maria Sharapova in 2004 — the year Gauff was born.

Thus, the young American takes home a record-setting $4.805 million, while Zheng pockets a (still) cool $2.305 million.

Gauff continues to be a lethal closer. She has played eight WTA Tour finals on hard courts — and won them all. She is the first woman to do that in more than a half-century of Open Era play.

Earlier, Gauff beat the No.1-and No.2-ranked players in a span of three days, both times in straight sets. With those wins over Aryna Sabalenka and Iga Swiatek, Gauff is the youngest player to defeat the WTA’s top two at the same event since Maria Sharapova defeated Amelie Mauresmo and Justine Henin at the US Open in 2006.

Going into her match here Swiatek, the head-to-head was a daunting 11-1 — in favor of Swiatek. Gauff explained her success with a single word: pettiness.

“I think that’s really the answer,” she said, smiling. “I think I just love to say I’m right. Specifically today, I got comments about how I was going to lose badly today, so I was just like, OK, we’ll see. 

“I think it’s just, honestly just liking the idea of just proving people wrong and, and letting your racket do the talking. And so, yeah, I use it as motivation.”

You could see it on Saturday.

The raucous crowd at King Saud University Arena was primed for the match and the two players delivered. There were taut points, some brilliant defending from Gauff and hard flat shots from Zheng on both sides. The pattern held until the final point when, on her fifth match point, Gauff dashed to the net, scooped a low, sidespin shot just out of Zheng’s reach. As it landed, Gauff collapsed to the ground — exhausted, elated, victorious.

The two youngest players in the field reached the finals. Gauff and Zheng’s combined age of 42 years added up to their being the youngest finalists at the WTA Finals since Maria Sharapova and Serena Williams two decades ago.

Gauff and Zheng faced each other in the final of the Orange Bowl girls’ 18s singles tournament at the end of 2018. Gauff, then 14, won the match in three sets over the 16-year-old Zheng, becoming the youngest champion of the event in 15 years. 

“It’s pretty cool that we’re playing on the second-biggest stage and final in tennis,” Gauff said. “Six years later, here we are.”

And once again, it was Gauff in three sets. Prodigies tend to reveal themselves early — and now, at the highest level, it’s Gauff’s time.