Coco Gauff is through to her maiden WTA final as the teenager defeated Andrea Petkovic of Germany 6-4 6-4 in the semi-final of the Linz Open.

The 15-year-old becomes the youngest female to reach a final since Czech player Nicole Vaidisova in 2004.

But she only got into the event as a lucky loser after an injury to former Wimbledon winner Angelique Kerber.

"This is crazy, I thought I was out of the tournament in qualifying," said the American.

Currently ranked 110th, Gauff showed real determination to save nine out of the 10 break points she faced, before she sealed victory on her second match point.

In the final on Sunday, the girl from Florida will play either former French Open winner Jelena Ostapenko of Lativa or Russia's Ekaterina Alexandrova.