LINZ, Austria – American teenager Coco Gauff sealed a place in her first WTA quarterfinal at the Upper Austria Ladies’ Linz on Wednesday when Ukrainian Kateryna Kozlova retired in the final set of their second round match with a left lower leg injury. 

After getting into the main draw following the withdrawal of No.6 seed Maria Sakkari, Gauff beat Stefanie Voegele on Tuesday on what she called her “lucky day,” but needed to use all of her skills to battle back against the Ukrainian No.4 on Centre Court.

Read more: ‘Today was my lucky day’ – Gauff vanquishes Voegele in second shot at Linz

From a set and a break down at 6-4, 3-2, Gauff won four of the next five games to force a final set, and claimed eight of the first nine points of the decider before Kozlova could no longer continue, with the scoreboard reading 4-6, 6-4, 2-0 in favor of the 15-year-old.