Stefan Luckanov defeated Mert Ramadan 7-6 6-2 in the M15 Sozopol 3 q64 on hard. The upset overturned the form book — Mert Ramadan came in leading the head-to-head 1–0. Stefan Luckanov claimed a first win over Mert Ramadan in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2021-09-13 | M15 Sozopol 1 | Q32 | hard | Mert Ramadan | 6-1 6-4 |