Stadium: Court 4 Round: 26 Ground: Clay
| ITF M15 Vejle | 2021/07/28 10:25 | Ergi Kirkin v Andrea Del Federico | 3-6,6-2,6-2 |
| Challenger Nur-Sultan | 2021/07/20 09:10 | Ergi Kirkin v Ryan Peniston | 2-6,3-6 |
| Challenger Nur-Sultan | 2021/07/19 06:10 | Ergi Kirkin v Benjamin Lock | 5-7,7-6,3-6 |
| Challenger Nur-Sultan | 2021/07/12 04:00 | Ergi Kirkin v Oleksii Krutykh | 1-6,6-7 |
| Challenger Nur-Sultan | 2021/07/11 04:00 | Ergi Kirkin v Timur Mukhtarulin | 6-2,6-0 |
| ITF M25 Alkmaar | 2021/06/23 11:15 | Ergi Kirkin v Marko Tepavac | 4-6,3-6 |
| Challenger Almaty | 2021/06/15 11:50 | Zizou Bergs v Ergi Kirkin | 6-4,5-7,6-2 |
| Challenger Almaty | 2021/06/14 04:00 | Ergi Kirkin v Vladyslav Manafov | 6-2,6-3 |
| ITF M15 Vejle | 2021/07/27 09:15 | Marius Ruzgas v Alexander Kotzen | 2-6,6-4,3-6 |
| ITF M15 Esch/Alzette | 2021/07/22 13:10 | Tommaso Compagnucci v Alexander Kotzen | 6-2,6-0 |
| ITF M15 Esch/Alzette | 2021/07/21 10:55 | Alexander Kotzen v Louis Wessels | 2-6,6-3,6-4 |
| ITF M15 Esch/Alzette | 2021/07/20 11:00 | Benjamin Dhoe v Alexander Kotzen | 3-6,4-6 |
| ITF M15 Esch/Alzette | 2021/07/19 09:00 | Alexander Kotzen v Tibo Colson | 4-6,6-1,10-7 |
| ITF M15 Esch/Alzette | 2021/07/18 07:55 | Alexander Kotzen v Victor Ernaelsteen | 6-1,6-4 |
| ITF M15 Monastir | 2021/06/27 09:00 | Alexander Kotzen v Noah Lopez | 6-7,6-4,7-10 |
| ITF M15 Monastir | 2021/06/21 13:30 | Alexander Kotzen v Kody Pearson | 7-6,1-6,5-10 |