Stadium: Court 1 Round: 25 Ground: Clay
| ITF M15 Troisdorf | 2021/05/13 09:00 | Kai Wehnelt v Lucas Gerch | 4-6,6-4,5-7 |
| ITF M25 Wetzlar | 2021/08/04 08:00 | Harold Mayot v Kai Wehnelt | 6-4,6-7,7-5 |
| ITF M15 Cairo | 2021/07/29 08:00 | Gustavo Heide v Kai Wehnelt | 3-6,7-5,6-3 |
| ITF M15 Cairo | 2021/07/28 14:20 | Facundo Arias Bisso v Kai Wehnelt | 5-7,5-7 |
| ITF M15 Cairo | 2021/07/24 08:00 | Mathieu Perchicot v Kai Wehnelt | 6-3,1-6,7-5 |
| ITF M15 Cairo | 2021/07/23 07:55 | Kai Wehnelt v Lorenzo Bocchi | 3-6,6-4,6-2 |
| ITF M15 Cairo | 2021/07/22 08:00 | Kai Wehnelt v Leonid Sheyngezikht | 6-3,6-1 |
| ITF M15 Cairo | 2021/07/21 08:00 | Kai Wehnelt v Artur Soghoyan | 6-3,6-3 |
| ITF M25 Alkmaar | 2021/06/24 08:00 | Mats Rosenkranz v Kai Wehnelt | 6-1,4-6,5-7 |
| ITF M25 Wetzlar | 2021/08/04 09:55 | Daniel Cukierman v Lucas Gerch | 6-3,2-6,6-4 |
| Challenger Poznan | 2021/07/26 11:35 | David Poljak v Lucas Gerch | 7-5,1-6,6-4 |
| Challenger Poznan | 2021/07/25 10:30 | Sebastian Fanselow v Lucas Gerch | 2-6,5-7 |
| ITF M25 Hága | 2021/07/01 09:55 | Manuel Guinard v Lucas Gerch | 6-3,6-2 |
| ITF M25 Hága | 2021/06/29 11:20 | Lucas Gerch v Vladimir Ivanov | 6-1,6-2 |
| Challenger Forli | 2021/06/16 09:30 | Francesco Forti v Lucas Gerch | 6-4,6-4 |
| Challenger Forli | 2021/06/15 09:30 | Lucas Gerch v Thiago Agustin Tirante | 7-6,3-6,6-3 |
| Challenger Forli | 2021/06/14 09:30 | Lucas Gerch v Elmar Ejupovic | 4-6,6-4,7-6 |