| ITF Germany F9 | 2018/07/24 10:00 | Nico Mertens v Manuel Guinard | 0-6,6-4,4-6 |
| ITF Bosnia and Herzegovina F3 | 2018/05/29 10:40 | Nico Mertens v Nerman Fatic | 4-6,3-6 |
| ITF Czech Republic F2 Qual | 2018/05/21 08:00 | Nico Mertens v Michal Franek | 3-6,2-6 |
| ITF Czech Republic F2 Qual | 2018/05/20 08:00 | Nico Mertens v Radek Cyprich | 6-2,6-2 |
| ITF Tunisia F11 | 2018/03/19 08:30 | Nico Mertens v Jordi Munoz-Abreu | 1-6,3-6 |
| ITF Tunisia F11 | 2018/03/18 10:30 | Nico Mertens v Stefano Battaglino | 7-6,6-1 |
| ITF Tunisia F11 | 2018/03/17 08:00 | Nico Mertens v Miles Jones | 3-6,6-2,6-3 |
| ITF Tunisia F10 | 2018/03/15 11:20 | Nico Mertens v Mariano Kestelboim | 4-6,2-6 |
| ITF Germany F10 Qual | 2018/07/29 08:00 | Niklas Koch v Javier A V. Meza | 6-1,6-0 |
| ITF Turkey F11 | 2018/03/17 07:00 | Nicolas Xiviller v Niklas Koch | 6-0,6-1 |
| ITF Italy F36 Qual | 2017/10/28 13:00 | Niklas Koch v Harry Lim | 6-7,4-6 |
| ITF Italy F35 Qual | 2017/10/21 08:00 | Ottaviano Martini v Niklas Koch | 6-1,6-2 |
| ITF Germany F1 Qual | 2016/01/10 08:00 | Niklas Koch v Charly Zick | 6-4,4-6,1-6 |
| ITF Italy F32 Qual | 2015/10/17 10:30 | Arturo Schmidt v Niklas Koch | 6-2,6-3 |
| ITF Italy F30 | 2015/10/03 08:00 | Edoardo Lamberti v Niklas Koch | 6-1,6-4 |
| ITF Germany F9 | 2015/07/28 09:00 | Tom Schonenberg v Niklas Koch | 6-1,6-1 |