Stadium: Indoor 1 Round: 26 Ground: Clay
| 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 M25 Esch/Alzette | 2023/07/12 11:35 | Marcel Zielinski v Boris Fassbender | 6-3,6-1 |
| ITF M15 Sofia | 2023/07/06 08:10 | Matej Dodig v Marcel Zielinski | 6-4,6-2 |
| ITF M15 Sofia | 2023/07/05 09:45 | Alessandro Ingarao v Marcel Zielinski | 0-6,3-6 |
| ITF M15 Huy | 2023/08/23 15:25 | Felix Corwin v Antonio Cayetano March | 6-4,6-3 |
| ITF M15 Huy | 2023/08/21 16:35 | Felix Corwin v Martin Van Der Meerschen | 6-4,6-3 |
| ITF M15 Huy | 2023/08/21 11:00 | Felix Corwin v Oscar Galimardanov | 6-4,6-2 |
| ITF M15 Pittsburgh | 2023/07/30 14:00 | Felix Corwin v Juan Carlos Aguilar | 3-6,4-6 |
| ITF M15 Pittsburgh | 2023/07/28 15:00 | Felix Corwin v Bruno Kuzuhara | 6-3,6-4 |
| ITF M15 Pittsburgh | 2023/07/27 15:00 | Kousuke Ogura v Felix Corwin | 6-2,5-7,1-6 |
| ITF M15 Pittsburgh | 2023/07/25 16:00 | Evan Bynoe v Felix Corwin | 3-6,5-7 |
| ITF M25 The Hague | 2023/07/05 15:15 | Felix Corwin v Ryan Nijboer | 3-6,4-6 |