| UTR Pro Tennis Series - Mulheim | 2021/07/28 11:00 | Mark Wallner v Tim Sandkaulen | 6-7,5-6 |
| UTR Pro Tennis Series - Mulheim | 2021/07/27 09:30 | Mark Wallner v Matthew Thomson | 7-6,7-6 |
| UTR Pro Tennis Series - Mulheim | 2021/07/26 11:00 | Billy Harris v Mark Wallner | 7-6,7-6 |
| UTR Pro Tennis Series - Mulheim | 2021/07/29 07:00 | Matthew Thomson v Guy Den Heijer | 1-6,3-6 |
| UTR Pro Tennis Series - Mulheim | 2021/07/27 09:30 | Billy Harris v Guy Den Heijer | 3-6,2-6 |
| UTR Pro Tennis Series - Mulheim | 2021/07/26 11:00 | Guy Den Heijer v Tim Sandkaulen | 7-5,6-3 |
| ITF - Marburg M25 | 2021/07/07 10:50 | Aleksandre Metreveli v Guy Den Heijer | 6-3,1-6,6-2 |
| ITF - Marburg M25 | 2021/07/06 12:25 | Guy Den Heijer v Florian Broska | 6-3,7-6 |
| ITF - Marburg M25 | 2021/07/05 08:00 | Guy Den Heijer v Maximilian Homberg | 6-7,6-2,10-8 |
| ITF - Haga M25 | 2021/06/29 15:00 | Dayne Kelly v Guy Den Heijer | 6-1,6-4 |
| ITF - Haga M25 | 2021/06/28 09:40 | Guy Den Heijer v Max Van Nunen | 6-3,6-1 |