Stadion: Court 6 Round: 25 Ground: Hardcourt outdoor
| ITF - M15 - Monastir | 2021/08/17 07:30 | Federico Salomone v Kai Lemstra | 4-6,6-4,8-10 |
| ITF - M15 - Monastir | 2021/08/16 07:30 | Kai Lemstra v Blake Ellis | 6-4,6-3 |
| ITF - M25 - Wetzlar | 2021/08/02 14:00 | Osman Torski v Kai Lemstra | 6-4,0-6,10-5 |
| ITF - M25 - Most | 2021/05/26 10:15 | Antoine Escoffier v Kai Lemstra | 6-3,7-5 |
| ITF - M25 - Most | 2021/05/25 10:15 | Kai Lemstra v Edward Hubner | 6-1,6-1 |
| ITF - M25 - Most | 2021/05/24 08:00 | Kai Lemstra v Niklas Rohrer | 6-3,6-2 |
| ITF - M25 - Most | 2021/05/23 14:00 | Kai Lemstra v Vojtech Petr | 6-4,6-4 |
| ITF - M25 - Jablonec Nad Nisou | 2021/05/18 07:30 | Andrew Paulson v Kai Lemstra | 6-3,6-4 |
| ITF - M15 - Monastir | 2021/08/17 07:30 | Ishaan Ravichander v Duarte Vale | 4-6,5-7 |
| ITF - M15 - Monastir | 2021/08/16 07:30 | Mousa Alkotop v Duarte Vale | 2-6,3-6 |
| ITF - M15 - Monastir | 2021/08/15 09:30 | Boopathy Sakthivel v Duarte Vale | 0-6,0-6 |
| ITF - M15 - Monastir | 2021/08/08 08:30 | Daniil Glinka v Duarte Vale | 6-3,3-6,10-2 |
| ITF - M15 - Castelo Branco | 2021/07/30 08:30 | Duarte Vale v Joao Lucas Reis da Silva | 7-6,4-6,5-7 |
| ITF - M15 - Castelo Branco | 2021/07/29 08:30 | Martin Breysach v Duarte Vale | 2-6,4-6 |
| ITF - M15 - Castelo Branco | 2021/07/27 14:05 | Miguel Damas v Duarte Vale | 6-7,3-6 |
| ITF - M25 - Idanha-A-Nova | 2021/07/20 11:15 | Simon Carr v Duarte Vale | 6-4,7-6 |