Stadium: Court 1 Round: 25 Ground: Clay
| ITF M15 Frankfurt Am Main | 2023/08/10 10:55 | Kai Lemstra v Johannes Haerteis | 7-5,4-6,2-6 |
| ITF M15 Frankfurt Am Main | 2023/08/08 09:00 | Kai Lemstra v Matthew William Donald | 6-3,6-1 |
| ITF M15 Metzingen | 2023/07/28 10:50 | Kai Lemstra v Sander Jong | 6-3,0-6,2-6 |
| ITF M15 Metzingen | 2023/07/27 15:00 | Kai Lemstra v Juan C P Angelo | 7-5,6-0 |
| ITF M15 Metzingen | 2023/07/26 12:30 | Stefanos Sakellaridis v Kai Lemstra | 3-6,3-6 |
| ITF M15 Tanger | 2023/06/08 11:00 | Kai Lemstra v Constantin Bittoun Kouzmine | 3-6,3-6 |
| ITF M15 Tanger | 2023/06/07 14:00 | Maik Steiner v Kai Lemstra | 1-6,5-7 |
| ITF M15 Constanta | 2023/05/30 11:00 | Simon A Ivanov v Kai Lemstra | 6-2,6-2 |
| ITF M15 Ueberlingen | 2023/08/18 11:30 | Arthur Nagel v Adrian Oetzbach | 6-1,6-4 |
| ITF M15 Ueberlingen | 2023/08/17 13:40 | Adrian Oetzbach v Luca Wiedenmann | 6-2,7-5 |
| ITF M15 Ueberlingen | 2023/08/16 09:40 | Philip Florig v Adrian Oetzbach | 2-6,7-5,5-7 |
| Challenger Meerbusch | 2023/08/06 15:45 | Tibo Colson v Adrian Oetzbach | 7-6,7-6 |
| ITF M15 Eindhoven | 2023/08/05 09:00 | Elmer Moller v Adrian Oetzbach | 7-6,6-7,6-7 |
| ITF M15 Eindhoven | 2023/08/04 10:00 | Stijn Paardekooper v Adrian Oetzbach | 3-6,6-3,2-6 |
| ITF M15 Eindhoven | 2023/08/03 09:00 | Jurriaan Bol v Adrian Oetzbach | 3-6,3-6 |
| ITF M15 Eindhoven | 2023/08/02 10:45 | Adrian Oetzbach v Sidane Pontjodikromo | 6-3,6-0 |