Stadium: Court 2 Round: 25 Ground: Clay
| Challenger - Praha | 2021/08/27 09:00 | Franco Agamenone v Igor Sijsling | 6-3,6-0 |
| Challenger - Praha | 2021/08/26 10:00 | Igor Sijsling v Kaichi Uchida | 7-5,6-3 |
| Challenger - Praha | 2021/08/24 13:45 | Daniel Siniakov v Igor Sijsling | 4-6,3-6 |
| Challenger - Segovia | 2021/07/27 14:25 | Igor Sijsling v Teymuraz Gabashvili | 1-6,3-6 |
| Challenger - Pozoblanco | 2021/07/22 16:00 | Tim Van Rijthoven v Igor Sijsling | 6-4,6-4 |
| Challenger Iasi | 2021/07/12 11:50 | Felipe Meligeni Rodrigues Alves v Igor Sijsling | 7-5,6-2 |
| Challenger Braunchsweig | 2021/07/04 10:10 | Igor Sijsling v Diego Hidalgo | 3-6,6-3,4-6 |
| Challenger Forli | 2021/06/16 11:15 | Mats Moraing v Igor Sijsling | 3-6,6-4,6-2 |
| Challenger Kiiev | 2021/09/06 11:35 | Matheus P De Almeida v Michael Vrbensky | 6-3,6-2 |
| Challenger Varssavi | 2021/08/28 09:00 | Michael Vrbensky v Nino Serdarusic | 6-7,2-6 |
| Challenger Varssavi | 2021/08/26 13:05 | Michael Vrbensky v Jeroen Vanneste | 6-0,4-6,6-3 |
| Challenger Varssavi | 2021/08/25 09:35 | Vitaliy Sachko v Michael Vrbensky | 6-2,6-7,4-6 |
| Challenger Luedenscheid | 2021/08/17 11:35 | Juan Manuel Cerundolo v Michael Vrbensky | 6-4,6-2 |
| Challenger - Praha | 2021/08/10 12:00 | Michael Vrbensky v Evgeny Tyurnev | 4-6,2-6 |
| Challenger - Liberec | 2021/08/02 13:35 | Michael Vrbensky v Marc Polmans | 7-6,2-6,5-7 |
| Challenger Trieste | 2021/07/27 13:00 | Flavio Cobolli v Michael Vrbensky | 7-6,6-3 |