Coco Gauff hit another big milestone by reaching her first WTA Tour final at the Upper Austria Ladies Linz.

The 15-year-old became the youngest woman since Nicole Vaidisova won a title in Tashkent 15 years ago to make the last four of a tournament by knocking out top seed Kiki Bertens on Friday.

And she was in fine form again to see off German Andrea Petkovic 6-4 6-4 and set up a final clash with former French Open champion Jelena Ostapenko.

The Latvian has endured a miserable season and has dropped outside the top 70 but, working with former Wimbledon winner Marion Bartoli, this week has seen a resurgence.

Ostapenko took on last year's runner-up Ekaterina Alexandrova from Russia and recovered from a poor first set to prevail 1-6 7-6 (5) 7-5 to reach her first WTA final since Miami last spring.