FILE - In this August 2019, file photo, Coco Gauff, of the United States, celebrates after defeating Timea Babos, of Hungary, in the second round of the U.S. Open tennis tournament in New York. Photo: Charles Krupa/AP

STUTTGART  American tennis sensation Cori Gauff claimed her first WTA title on Sunday at age 15 by defeating former French Open champion Jelena Ostapenko 6-3, 1-6, 6-2 at the Upper Austria Ladies Linz tournament.

Gauff burst onto the scene this year by reaching the last 16 at Wimbledon and according to the WTA is the youngest tour winner since Nicole Vaidisova of the Czech Republic in 2004.

In Sunday's final Gauff looked on course for victory when leading 5-0 in the deciding set but a mini-comeback from Latvia's Ostapenko to 5-2 tested her nerve.

The win completes a remarkable week for Gauff who actually lost to German Tamara Korpatsch in the qualifying final and was included in the competition as a lucky loser.

Gauff enter the top 100 of the world rankings for the first time on Monday when they are released by the WTA.