Stadium: Court 7 Round: 25 Ground: Clay
| Challenger - Lüdenscheid | 2021/08/15 09:30 | Bogdan Bobrov v Johannes Haerteis | 1-6,6-4,6-3 |
| Challenger - Meerbusch | 2021/08/08 16:05 | Ivan Nedelko v Johannes Haerteis | 7-6,6-3 |
| Challenger - Segovia | 2021/07/27 13:05 | Altug Celikbilek v Johannes Haerteis | 6-3,6-4 |
| Challenger - Pozoblanco | 2021/07/20 20:10 | Cem Ilkel v Johannes Haerteis | 6-2,7-6 |
| Challenger - Amersfoort | 2021/07/13 08:30 | Mats Moraing v Johannes Haerteis | 6-1,6-0 |
| Challenger - Braunschweig | 2021/07/04 11:55 | Johannes Haerteis v Nino Ehrenschneider | 6-3,3-6,4-6 |
| Challenger - Prostejov | 2021/06/15 08:30 | Johannes Haerteis v Federico Coria | 1-6,0-6 |
| Challenger - Prostejov | 2021/06/14 08:30 | Johannes Haerteis v David Poljak | 5-7,3-6 |
| Challenger - Prag | 2021/08/23 08:00 | Nick Hardt v Alex Rybakov | 6-7,3-6 |
| Challenger - Prag | 2021/08/22 08:00 | Marek Gengel v Alex Rybakov | 5-7,1-6 |
| ITF M25 - Prostejov | 2021/08/20 08:00 | Nikolas Sanchez Izquierdo v Alex Rybakov | 6-3,6-2 |
| ITF M25 - Prostejov | 2021/08/19 08:15 | Alex Rybakov v Nick Chappell | 6-2,7-6 |
| ITF M25 - Prostejov | 2021/08/18 07:55 | Alex Rybakov v Marek Gengel | 6-3,6-3 |
| ITF M25 - Prostejov | 2021/08/17 09:00 | Alex Rybakov v David Poljak | 7-6,7-6 |
| ITF M25 - Decatur | 2021/08/07 14:45 | Eliot Spizzirri v Alex Rybakov | 6-4,7-5 |
| ITF M25 - Decatur | 2021/08/06 15:00 | Alex Rybakov v Gijs Brouwer | 7-5,6-3 |