Ground: Clay
| ITF M15 Trier | 2025/08/13 12:30 | Marcel Zielinski v Michael Agwi | 3-6,1-6 |
| ITF M15 Eupen | 2025/08/10 13:00 | Emilien Demanet v Marcel Zielinski | 7-5,7-5 |
| ITF M15 Eupen | 2025/08/09 12:00 | Marcel Zielinski v Simon Beaupain | 6-3,6-1 |
| ITF M15 Eupen | 2025/08/08 17:00 | Adrien Gobat v Marcel Zielinski | 4-6,1-6 |
| ITF M15 Eupen | 2025/08/07 15:00 | Marcel Zielinski v Daniel Verbeek | 6-2,7-5 |
| ITF M15 Eupen | 2025/08/06 10:30 | Marcel Zielinski v Leo Lagarrigue | 7-6,5-2 |
| ITF M15 Xativa | 2025/07/31 08:00 | Marcel Zielinski v Pedro Rodenas | 4-6,4-5 |
| ITF M15 Xativa | 2025/07/29 14:23 | Marcel Zielinski v Mario Arce Fernandez | 6-3,6-0 |
| ITF M15 Telfs | 2025/07/10 11:41 | Jonas P Hartenstein v Karl Friberg | 2-6,3-6 |
| ITF M15 Telfs | 2025/07/09 13:56 | Jonas P Hartenstein v Andrea De Marchi | 6-0,1-6,6-0 |
| ITF M15 Kamen | 2025/06/25 10:30 | Daniel Siniakov v Jonas P Hartenstein | 5-7,6-2,6-3 |
| ITF M15 Saarlouis | 2025/06/19 09:30 | Jonas P Hartenstein v Adrian Oetzbach | 1-6,3-6 |
| ITF M15 Saarlouis | 2025/06/18 11:30 | Jonas P Hartenstein v Nikolai Barsukov | 6-3,6-3 |
| ITF M15 Heraklion | 2025/04/02 10:29 | Jonas P Hartenstein v Alexis Canter | 2-6,7-6,6-7 |
| ITF M15 Heraklion | 2025/03/26 12:58 | Marcus Walters v Jonas P Hartenstein | 7-6,6-3 |
| ITF M25 Trimbach | 2025/03/05 15:17 | Jonas P Hartenstein v Mats Rosenkranz | 2-6,5-7 |