Hannah Roberts held off fellow American Perris Benegas to claim victory at the International Cycling Union BMX Freestyle World Cup in Montpellier.
Roberts and Benegas had been in the top two throughout qualification and semi-final stages and were the final two riders on the park in France on Saturday.
The 17-year-old came out on top with a score of 93.00 from her two runs, beating Benegas, 23, into second after she scored 90.60.
German rider Lara Lessman, 19, claimed third place after a pair of impressive performances in the final, edging Switzerland's Nikita Ducarroz into fourth.
Japan's Oike Minato, who won in Montpellier last year, was sixth, while Britain's Charlotte Worthington – having qualified in third – came seventh.
It also puts Roberts firmly in control of the World Series rankings, after she claimed titles in 2017 and 2018.
When you win the trophy but the trophy not having it 👋 pic.twitter.com/zfXg7Rvalo— FISE (@fiseworld) 1 June 2019
Her victories in Hiroshima on stop one as well as in France mean she has a perfect overall score of 10 points heading into the final stop of the tour in Chengdu.
Lessman and Benegas are the only riders in with a chance of overhauling Roberts, tied on 17.2.
Later on Saturday, the men's BMX freestyle semi-finals saw most of the big names, including Logan Martin, Brandon Loupos and Rim Nakamura, progress.
A notable performer was New Zealand's Kyle Baldock, who qualified 24th of 24 in the first stage, but posted the fourth-best score after a brilliant ride, scored at 91.4, in the first outing of the semi-final.
There was also delight for the home crowd as Anthony Jeanjean – the only Frenchman in the semi-final – snuck his way into Sunday's showpiece with the 12th-best score.
The final starts at 3pm local time on Sunday.