Stadium: Court 1 Round: 25 Ground: Hardcourt outdoor
| ITF Israel F16 | 2017/11/30 08:00 | Constantin Bittoun Kouzmine v Mertens, Yannick | 1-6,3-6 |
| Challenger Mallorca | 2018/08/26 10:45 | Mertens, Yannick v Simon, Tobias | 7-6,4-6,4-6 |
| ITF Netherlands F4 | 2018/08/16 10:30 | Mertens, Yannick v Kazuki Nishiwaki | 3-6,6-7 |
| ITF Netherlands F4 | 2018/08/14 14:15 | Mertens, Yannick v Sidane Pontjodikromo | 6-1,4-6,6-4 |
| Challenger Pullach Qual | 2018/08/04 15:25 | Mertens, Yannick v Steven Diez | 2-6,2-6 |
| Challenger Astana | 2018/07/17 07:45 | Mertens, Yannick v Jurij Rodionov | 5-7,0-6 |
| ITF France F13 | 2018/07/13 17:20 | Mertens, Yannick v Sora Fukuda | 6-2,3-6,4-6 |
| ITF France F13 | 2018/07/12 18:30 | Mertens, Yannick v Lakat, Florian | 6-3,6-4 |
| ITF France F13 | 2018/07/10 13:40 | Mertens, Yannick v Voljacques, Hugo | 6-2,6-2 |
| ITF Belgium F7 | 2018/08/10 15:30 | Vanneste, Jeroen v Constantin Bittoun Kouzmine | 6-2,6-3 |
| ITF Belgium F7 | 2018/08/08 11:00 | Borg, Maikel v Constantin Bittoun Kouzmine | 3-6,6-7 |
| ITF Belgium F7 | 2018/08/07 08:30 | Peters, Flemming v Constantin Bittoun Kouzmine | 3-6,4-6 |
| ITF Belgium F6 | 2018/07/31 13:05 | Constantin Bittoun Kouzmine v Wojcik, Jakub | 1-6,6-4,4-6 |
| ITF France F15 | 2018/07/28 13:00 | Constantin Bittoun Kouzmine v Santanna, B. | 5-7,4-6 |
| ITF France F15 | 2018/07/27 10:00 | Constantin Bittoun Kouzmine v Joffrey De Schepper | 6-4,4-6,6-0 |
| ITF France F15 | 2018/07/26 09:35 | Voljacques, Hugo v Constantin Bittoun Kouzmine | 7-5,4-6,4-6 |
| ITF France F15 | 2018/07/24 15:30 | Constantin Bittoun Kouzmine v de La Bassetiere, Constant | 6-3,6-2 |