Teenager Joao Fonseca beat American Learner Tien to be crowned the second-youngest winner of the Next Gen ATP Finals title.

The 18-year-old Brazilian, who was the youngest player in this year's competition and lowest ranked, overcame Tien 2-4 4-3 (10-8) 4-0 4-2 in Jeddah.

Only Jannik Sinner, in 2019, has lifted the title at a younger age than Fonseca, who won all five of his matches at the season-ending tournament for the top-ranked male players aged 21 and under.

The pair also met in the group stage on Thursday, with Fonseca, ranked 145th in the world, again coming out on top against his 19-year-old opponent.

The event has a best-of-five format with four games winning a set.

As well as world number one Sinner, other former champions include four-time Grand Slam winner Carlos Alcaraz and world number 11 Stefanos Tsitsipas.

Tien started brightly and took the opening set in Saudi Arabia. But once Fonseca got himself level after a tight second set that went into a long tie-break, he was able to frustrate his opponent and seal the title in the fourth set.

"I was really nervous before the match. I knew it was going to be so difficult," Fonseca said.

"I played a final against Learner in juniors at the 2023 US Open and I know the way he can play. He is such a nice guy and a great player, so I knew it was going to be difficult, mentally and physically. But I got through."

Speaking before the final, Fonseca spoke of how he wanted to emulate Sinner, for whom he was a hitting partner at last year's ATP Finals - where he said he was convinced by the Italian to turn professional.