Stadium: Central Court Round: 26 Ground: Clay
| Challenger Szczecin | 2021/09/14 15:25 | Albert Ramos-Vinolas v Nicola Kuhn | 6-1,4-6,4-6 |
| Challenger Szczecin | 2021/09/13 12:10 | Nicola Kuhn v Matteo Martineau | 6-4,6-1 |
| Challenger Szczecin | 2021/09/12 14:35 | Nicola Kuhn v Nathaniel Lammons | 6-3,6-4 |
| Challenger Seville | 2021/09/07 10:50 | Gian Marco Moroni v Nicola Kuhn | 7-6,6-1 |
| Challenger Meerbusch | 2021/08/10 08:30 | Nicola Kuhn v Nick Hardt | 6-4,6-3 |
| ATP Hamburg | 2021/07/12 10:30 | Nicola Kuhn v Thiago Seyboth Wild | 6-1,1-6,2-6 |
| Challenger Braunschweig | 2021/07/07 11:40 | Nicola Kuhn v Henri Laaksonen | 4-6,5-7 |
| Challenger Braunschweig | 2021/07/06 15:25 | Nicola Kuhn v Mischa Zverev | 6-2,7-6 |
| Challenger Szczecin | 2021/09/14 10:00 | Danilo Petrovic v Alex Rybakov | 1-6,2-6 |
| Challenger Szczecin | 2021/09/13 09:00 | Jesper De Jong v Alex Rybakov | 6-3,3-6,2-6 |
| Challenger Szczecin | 2021/09/12 09:00 | Szymon Kielan v Alex Rybakov | 2-6,6-2,3-6 |
| Challenger Kyiv | 2021/09/09 08:00 | Sebastian Baez v Alex Rybakov | 6-4,6-2 |
| Challenger Kyiv | 2021/09/07 07:00 | Alex Rybakov v Mohamed Aziz Dougaz | 5-7,6-0,6-3 |
| Challenger Kyiv | 2021/09/06 08:00 | Alex Rybakov v Aleksandr Braynin | 6-3,6-4 |
| Challenger Kyiv | 2021/09/05 08:00 | Alex Rybakov v Nikita Mashtakov | 6-2,6-2 |
| Challenger Prague | 2021/08/25 12:25 | Michael Geerts v Alex Rybakov | 6-2,6-2 |