Natalija Kostic defeated Xenia Knoll 6-7 6-4 6-0 in the Belgrade 10K qualifying round on clay. The upset overturned the form book — Xenia Knoll came in leading the head-to-head 1–0. Natalija Kostic claimed a first win over Xenia Knoll in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2013-09-02 | Belgrade 10K | F | clay | Xenia Knoll | 6-3 6-3 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.