| Internazionali di Polonia - Qual. | 2021/09/23 11:40 | Aaron Sonnenschein v Tarun Reddy Katam | W | 0-2 |
| Internazionali di Polonia - Qual. | 2021/09/23 12:00 | Gal Bizjak v Karl Kert | W | 0-2 |
| Internazionali di Lettonia | 2021/08/27 11:00 | Bernardo Atilano v Karl Kert | L | 2-0 |
| Internazionali di Lituania | 2021/06/11 09:40 | Alvaro Vazquez v Karl Kert | L | 2-0 |
| Open d'Austria - Qual. | 2021/05/27 14:20 | Karl Kert v Magnus Johannesen | L | 1-2 |
| Open d'Austria - Qual. | 2021/05/27 10:00 | Samuel Cassar v Karl Kert | W | 0-2 |
| Slovenia Int. | 2021/05/20 12:00 | Ivan Rusev v Karl Kert | L | 2-0 |
| Portuguese Int. Qual | 2021/05/06 12:00 | Martin Bundgaard v Karl Kert | L | 2-1 |
| Portuguese Int. Qual | 2021/05/06 08:20 | Alvaro Leal v Karl Kert | W | 0-2 |