Stadium: Clay 5 Round: 26 Ground: Hardcourt outdoor
| ITF Serbia F2 | 2018/08/15 08:00 | Gabriel Donev v Duje Ajdukovic | 6-3,4-6,2-6 |
| ITF Belgium F5 | 2018/07/24 14:00 | Colin Sinclair v Gabriel Donev | 6-3,6-4 |
| ITF Germany F5 | 2018/06/28 11:00 | Gabriel Donev v Filip Bergevi | 2-6,4-6 |
| ITF Germany F5 | 2018/06/27 11:35 | Alexander Igoshin v Gabriel Donev | 2-6,2-6 |
| ITF Germany F5 | 2018/06/25 08:00 | Gabriel Donev v August Holmgren | 6-2,7-6 |
| ITF Germany F5 | 2018/06/25 08:00 | Gabriel Donev v Karlo Cubelic | 6-2,6-2 |
| ITF Romania F1 | 2018/05/22 09:20 | Gabriel Donev v Mathieu Perchicot | 3-6,1-6 |
| ITF Bulgaria F1 | 2018/05/18 09:10 | Calin Manda v Gabriel Donev | 6-1,2-6,6-2 |
| Challenger Portoroz | 2018/08/07 14:00 | Nik Razborsek v Dominik Koepfer | 7-6,5-7,6-7 |
| Challenger Liberec | 2018/07/31 14:00 | Pedro Martinez v Nik Razborsek | 6-3,4-6,6-3 |
| Challenger Liberec Qual | 2018/07/30 09:00 | Marvin Moeller v Nik Razborsek | 4-6,6-7 |
| Challenger Liberec Qual | 2018/07/29 08:30 | Martin Bugaj v Nik Razborsek | 2-6,0-6 |
| Challenger Tampere Qual | 2018/07/22 11:45 | Nik Razborsek v Markus Eriksson | 3-6,4-6 |
| Challenger Tampere | 2018/07/21 13:55 | Kristjan Tamm v Nik Razborsek | 6-2,3-6,6-7 |
| ATP Umag Qual | 2018/07/15 10:00 | Alexey Vatutin v Nik Razborsek | 6-2,6-3 |
| ITF Italy F14 | 2018/06/16 14:00 | Nik Razborsek v Riccardo Bellotti | 4-6,3-6 |