| UTR Pro Tennis Series Mulheim | 2021/09/25 10:00 | Colin Sinclair v Jing L Weng | 6-1,6-4 |
| UTR Pro Tennis Series Mulheim | 2021/09/23 11:00 | Colin Sinclair v Jurriaan Bol | 6-3,6-3 |
| UTR Pro Tennis Series Mulheim | 2021/09/22 14:00 | Colin Sinclair v Christos Keisidis | 6-3,6-1 |
| UTR Pro Tennis Series Mulheim | 2021/09/21 08:00 | Colin Sinclair v Artem Podorozhnyi | 5-7,4-6 |
| UTR Pro Tennis Series Mulheim | 2021/09/20 09:30 | Colin Sinclair v Edison Ambarzumjan | 7-5,5-4 |
| Davis Cup | 2021/09/18 08:15 | Kareem Allaf v Colin Sinclair | 5-7,7-6,4-6 |
| Davis Cup | 2021/09/17 08:50 | Mousa Shanan Zayed v Colin Sinclair | 1-6,0-6 |
| Davis Cup | 2021/09/15 09:20 | Nam Hoang Ly v Colin Sinclair | 4-6,6-4,4-6 |
| UTR Pro Tennis Series Mulheim | 2021/09/25 08:30 | Mikhail Minakov v Guy Den Heijer | 3-6,6-6 |
| UTR Pro Tennis Series Mulheim | 2021/09/24 11:00 | Thijmen Loof v Guy Den Heijer | 3-6,2-6 |
| UTR Pro Tennis Series Mulheim | 2021/09/23 08:00 | Jose A R Rodriguez v Guy Den Heijer | 6-7,2-5 |
| UTR Pro Tennis Series Mulheim | 2021/09/21 13:00 | Buvaysar Gadamauri v Guy Den Heijer | 6-4,6-6 |
| UTR Pro Tennis Series Mulheim | 2021/09/20 12:30 | Guy Den Heijer v Lawrence Bataljin | 6-0,5-1 |
| ITF M25 Eupen | 2021/09/09 09:00 | Romain Faucon v Guy Den Heijer | 6-4,6-4 |
| ITF M25 Eupen | 2021/09/08 07:30 | Guy Den Heijer v Kai Wehnelt | 3-6,6-3,6-2 |
| ITF M25 Eupen | 2021/09/07 10:05 | Guy Den Heijer v Tom Gentzsch | 6-3,6-4 |