| UTR Pro Tennis Series Mulheim | 2021/09/24 08:00 | Christos Keisidis v Jurriaan Bol | 1-6,4-6 |
| UTR Pro Tennis Series Mulheim | 2021/09/23 11:00 | Christos Keisidis v Artem Podorozhnyi | 5-7,2-5 |
| 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 | Edison Ambarzumjan v Christos Keisidis | 6-2,4-6,5-1 |
| UTR Pro Tennis Series Sofia | 2021/09/03 07:00 | George Lazarov v Christos Keisidis | 6-4,6-4 |
| UTR Pro Tennis Series Sofia | 2021/09/02 07:00 | Vladimir Popov v Christos Keisidis | 7-6,6-7,3-6 |
| UTR Pro Tennis Series Sofia | 2021/09/01 08:00 | Christos Keisidis v Mario Radev | 6-1,4-6,6-4 |
| UTR Pro Tennis Series Sofia | 2021/08/31 08:00 | Christos Keisidis v Josh Sheehy | 4-6,4-6 |
| UTR Pro Tennis Series Mulheim | 2021/09/25 07:00 | Julien De Cuyper v Lawrence Bataljin | 0-6,0-6 |
| UTR Pro Tennis Series Mulheim | 2021/09/24 11:00 | Jose A R Rodriguez v Lawrence Bataljin | 3-6,6-2,5-1 |
| UTR Pro Tennis Series Mulheim | 2021/09/23 08:00 | Buvaysar Gadamauri v Lawrence Bataljin | 6-3,5-4 |
| UTR Pro Tennis Series Mulheim | 2021/09/22 09:30 | Thijmen Loof v Lawrence Bataljin | 6-3,5-3 |
| UTR Pro Tennis Series Mulheim | 2021/09/20 12:30 | Guy Den Heijer v Lawrence Bataljin | 6-0,5-1 |
| UTR Pro Tennis Series Ricany | 2021/09/19 07:00 | Lawrence Bataljin v Stefanos Sakellaridis | 0-6,6-6 |
| UTR Pro Tennis Series Ricany | 2021/09/18 07:30 | Lawrence Bataljin v Michael Gloeckler | 6-4,5-2 |
| UTR Pro Tennis Series Ricany | 2021/09/11 12:00 | Lawrence Bataljin v Jiri Jenicek | 1-6,1-5 |