STUTTGART, Germany (AP) — Coco Gauff battled her way to the quarterfinals of the Porsche Grand Prix on Wednesday with a hard-fought 6-3, 4-6, 7-5 win over compatriot Sachia Vickery.

The 134th-ranked Vickery created 19 break points but could only convert seven of them against the world No. 3. Gauff had 15 double faults in the match, but rallied from 4-2 down in the final set before winning in 2 hours, 26 minutes with her first match point.

Gauff, who received a first-round bye at the clay-court tournament, awaits the winner between No. 7 Zheng Qinwen and Marta Kostyuk.

Kostyuk earlier overcame former champion Laura Siegemund 6-3, 6-7 (4), 6-4 in their first-round match. The Ukrainian player twice served for the match in the second set only for Siegemund, who won in 2017, to take it to the third.

Ons Jabeur also had to fight hard to prevail in a 2-6, 6-3, 7-6 (1) win over Ekaterina Alexandrova of Russia. Jabeur was down a break in both the second and third sets before winning.