Round: 60 Ground: Hardcourt indoor
| ITF Germany F3 Qual | 2018/01/29 16:30 | Dominik Boehler v Kai Lemstra | 7-6,7-6 |
| ITF Germany F3 Qual | 2018/01/28 17:00 | Charley Emhardt v Kai Lemstra | 1-6,2-6 |
| ITF Germany F2 | 2018/01/23 15:35 | Kai Lemstra v Pedro Cachin | 3-6,3-6 |
| ITF Germany F1 | 2018/01/11 17:10 | Elmar Ejupovic v Kai Lemstra | 6-3,6-4 |
| ITF Germany F1 | 2018/01/10 11:45 | Stefan Seifert v Kai Lemstra | 6-2,6-7,4-6 |
| ITF Germany F1 | 2018/01/08 12:30 | Karlo Cubelic v Kai Lemstra | 6-4,2-6,4-6 |
| ITF Germany F1 | 2018/01/07 11:30 | Tim Heger v Kai Lemstra | 4-6,4-6 |
| Challenger Eckental Qual | 2017/10/28 13:30 | Benjamin Hassan v Kai Lemstra | 7-5,7-6 |