Rudolf Niklas Christiansen advanced when Dominique Graf retired 6-4 3-1 in the M25 Ueberlingen 1 q16. Rudolf Niklas Christiansen claimed a first win over Dominique Graf in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2025-05-20 | M15 Heraklion 6 | Q16 | hard | Dominique Graf | 6-3 6-3 |