Stadium: Cancha 1 Round: 25 Ground: Hardcourt outdoor
| ITF M15 Ithaca | 2021/11/04 16:45 | Colin Sinclair v Vasil Kirkov | 3-6,4-6 |
| ITF M15 Ithaca | 2021/11/03 17:55 | Michael Zheng v Colin Sinclair | 0-6,2-6 |
| ITF M15 Tallahassee | 2021/10/27 14:00 | Colin Sinclair v Ryan Shane | 6-3,3-6,6-7 |
| ITF M15 Ithaca | 2021/10/05 16:00 | Taha Baadi v Colin Sinclair | 7-6,7-5 |
| ITF M25 Budapest | 2021/09/28 10:45 | Pawel Juszczak v Colin Sinclair | 6-2,7-6 |
| UTR Pro Tennis Series Mulheim | 2021/09/25 13:30 | Colin Sinclair v Guy Den Heijer | 2-6,3-5 |
| 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 |