Stadium: Court 1 Round: 25 Ground: Clay
| ITF M15 Szczawno | 2023/08/31 14:35 | Patrick Zahraj v Marcel Zielinski | 6-3,6-3 |
| ITF M15 Szczawno | 2023/08/30 08:35 | Adam Majchrzak v Marcel Zielinski | 2-6,3-6 |
| ITF M15 Huy | 2023/08/25 08:00 | Marcel Zielinski v Felix Corwin | 6-1,1-6,3-6 |
| ITF M15 Huy | 2023/08/23 14:10 | Marcel Zielinski v Lautaro Agustin Falabella | 6-3,6-4 |
| ITF M15 Frankfurt Am Main | 2023/08/09 13:00 | Jakob Schnaitter v Marcel Zielinski | 6-7,6-2,6-2 |
| ITF M15 Eindhoven | 2023/08/03 11:20 | Elmer Moller v Marcel Zielinski | 6-3,6-1 |
| ITF M15 Eindhoven | 2023/08/01 15:20 | Alexis Boureau v Marcel Zielinski | 1-6,1-6 |
| ITF M25 Esch/Alzette | 2023/07/13 14:30 | Marcel Zielinski v Brian Bozemoj | 6-2,6-4 |
| ITF M15 Szczawno | 2023/08/30 13:30 | Alec Beckley v Bruno Kokot | 7-5,6-2 |