Stadium: Center Round: 27 Ground: Clay
| ITF M25 - Haag | 2023/07/06 16:45 | Collin Altamirano v Guy Den Ouden | 6-7,6-3,2-6 |
| ITF M25 - Haag | 2023/07/04 17:00 | Alec Deckers v Guy Den Ouden | 6-7,6-7 |
| ITF M15 - Alkmaar | 2023/06/29 12:05 | Jeffrey Von Der Schulenburg v Guy Den Ouden | 6-4,3-6,7-5 |
| ITF M15 - Alkmaar | 2023/06/28 11:30 | Deney Wassermann v Guy Den Ouden | 6-7,5-7 |
| ITF M25 - Risskov/Århus | 2023/06/17 09:00 | Guy Den Ouden v Leo Borg | 6-3,4-6,1-6 |
| ITF M25 - Risskov/Århus | 2023/06/16 09:55 | Max Houkes v Guy Den Ouden | 6-3,3-6,4-6 |
| ITF M25 - Risskov/Århus | 2023/06/15 08:30 | Philipp Pavlenko v Guy Den Ouden | 2-6,1-6 |
| ITF M25 - Risskov/Århus | 2023/06/14 08:25 | Carl Emil Overbeck v Guy Den Ouden | 1-6,2-6 |
| ITF M25 - Haag | 2023/07/06 14:05 | Aleksandr Braynin v Ryan Nijboer | 4-6,6-7 |
| ITF M25 - Haag | 2023/07/05 15:15 | Felix Corwin v Ryan Nijboer | 3-6,4-6 |
| ITF M15 - Alkmaar | 2023/06/30 12:05 | Ryan Nijboer v Sander Jong | 3-6,4-6 |
| ITF M15 - Alkmaar | 2023/06/29 10:30 | Ryan Nijboer v Teun Rozenberg | 6-4,6-7,6-3 |
| ITF M15 - Alkmaar | 2023/06/28 11:40 | Ryan Nijboer v Nicolas Kobelt | 6-2,6-1 |
| ITF M15 - Duffel | 2023/06/17 11:15 | Ryan Nijboer v Jeremy Jahn | 2-6,1-6 |
| ITF M15 - Duffel | 2023/06/16 11:00 | Ryan Nijboer v John Sperle | 6-4,4-6,6-3 |
| ITF M15 - Duffel | 2023/06/15 10:00 | Ryan Nijboer v Andrea Gola | 2-6,6-1,6-3 |