Brazilian 18-year-old Joao Fonseca is the ATP Next Gen Finals champion after coming from a set down to dispatch American prospect Learner Tien, 19, in Jeddah, Saudi Arabia.

Having saved a set point in the second-set tiebreak before winning it 10-8, Fonseca turned on the afterburners, using scarcely believable power on both groundstroke wings to take Tien’s racket out of his hands and triumph 2-4, 4-3(8), 4-0, 4-2. He wins $526,480 (£417,000) after going through the event undefeated, and becomes the second-youngest player ever to win it, after Jannik Sinner; Carlos Alcaraz is the third-youngest. He is the lowest-ranked champion in the history of the event, ranked No. 145 in the world at the start of the tournament.

“I think I was another Joao,” Fonseca said of the final two sets, adding that he had no idea how he had made it through the second.

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

Tien’s sharp angles and calm consistency had carried him to an unexpected finals berth, with the American leaning into his groundstrokes more and more as the week progressed. With Fonseca having beaten him easily in the round-robin stage (including two 4-0 sets) Tien’s fast start took the Brazilian by surprise. He pulled Fonseca all over the court, denying him time to get set and unleash his forehand and backhand, particularly the down-the-line shots which have wrecked opponents’ worlds all week. Fonseca hit 37 percent of his backhands down the line during the event; the tour average is 25 percent, per Tennis Viz.

“He’s got me the last few times, it’s tough”, Tien said during the trophy ceremony.

“I’ll try not to let this loss try to take me down a notch. I played some really good tennis this week,” he added.

Once Fonseca levelled proceedings, he looked the most likely winner. Tien, as Fonseca said in his on-court interview, tightened up from the ground and on serve, with his swinging left-handed delivery out wide to the ad court, so devastating all tournament — especially in beating world No. 20 Arthur Fils — looking more like its relatively low speed of around 99mph (156kmh). Tien made just over 80 percent of his first serves in the first and third set, but won over 80 percent of those points in the first set and just over 20 in the third.

Fonseca, now rolling, breezed to the third set and held steady until the fifth game of the fourth set. At 40-40 on Tien’s serve, sudden-death point, Fonseca hit the short, chipped return he used a few times to earn a rally off Tien’s serve and set up two huge groundstrokes: a backhand cross-court and an inside-out forehand. Tien could only slide the latter into the net, and despite one more point in the final game in which the American found the sharp angles and edges of the lines as he had done most of the week, a foray into the net with three match points in hand ended with Fonseca on the ground, hands over his face.

Nothing is guaranteed in tennis, and how much this means for his future will likely only be legible in hindsight. At the end, he stayed in the moment.

“I’m really proud of myself, the way that I played this week. Beating some really good players,” he said.

(Francois Nel / Getty Images)