Stadium: Court C Round: 25 Ground: Clay
| ITF M25 Ricany | 2021/09/01 09:05 | Marek Gengel v Daniel Siniakov | 7-5,6-3 |
| Challenger Prague | 2021/08/24 13:45 | Daniel Siniakov v Igor Sijsling | 4-6,3-6 |
| ITF M25 Prostejov | 2021/08/17 09:15 | Martin Krumich v Daniel Siniakov | 3-6,6-4,7-5 |
| Challenger Liberec | 2021/08/03 15:10 | Nikola Milojevic v Daniel Siniakov | 7-5,6-0 |
| Challenger Liberec | 2021/08/02 10:35 | Daniel Siniakov v David Vega Hernandez | 6-3,7-5 |
| Challenger Liberec | 2021/08/01 16:30 | Geoffrey Blancaneaux v Daniel Siniakov | 2-6,3-6 |
| ITF M15 Poprad | 2021/07/06 07:55 | Illya Beloborodko v Daniel Siniakov | 3-6,7-6,7-5 |
| ITF M15 Poprad | 2021/07/05 08:00 | Calin Manda v Daniel Siniakov | 3-6,0-6 |
| ITF M25 Pardubice | 2021/09/21 08:00 | Daniel Paty v Stefanos Sakellaridis | 3-6,3-6 |
| ITF M25 Pardubice | 2021/09/20 09:00 | Christopher Patzanovsky v Stefanos Sakellaridis | 6-4,1-6,7-10 |
| 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 10:30 | Stefanos Sakellaridis v Michalis Sakellaridis | 6-2,7-6 |
| UTR Pro Tennis Series Ricany | 2021/09/17 12:00 | Stefanos Sakellaridis v Petr Hajek | 6-7,2-6 |
| UTR Pro Tennis Series Ricany | 2021/09/11 10:30 | Dominik Kellovsky v Stefanos Sakellaridis | 7-5,5-1 |
| UTR Pro Tennis Series Ricany | 2021/09/09 07:30 | Dominik Suc v Stefanos Sakellaridis | 5-7,6-7 |
| UTR Pro Tennis Series Ricany | 2021/09/07 09:00 | Filip Duda v Stefanos Sakellaridis | 4-6,6-4,5-2 |