Sujin Yoon defeated Gayeong Back 0-6 6-1 6-2 in the Changwon 25K qualifying round of 32 on hard. The upset overturned the form book — Gayeong Back came in leading the head-to-head 1–0. Sujin Yoon claimed a first win over Gayeong Back in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2015-05-25 | Changwon $25K | Q32 | hard | Gayeong Back | 3-6 7-6(3) 6-3 |