Estadio: Opatija 3 Round: 26 Ground: Clay
| ITF Croacia F3 | 2018/03/21 15:05 | Kai Lemstra v Xin Hu | 6-2,6-1 |
| ITF Croacia F3 | 2018/03/20 09:00 | Kai Lemstra v Marcell Bartakovics | 6-0,3-6,6-1 |
| ITF Croacia F3 | 2018/03/19 12:30 | Kai Lemstra v Edoardo Pompei | 6-1,2-6,7-6 |
| ITF Croacia F3 | 2018/03/19 09:00 | Kai Lemstra v Michelangelo Endrizzi | 6-3,6-4 |
| ITF Croacia F2 | 2018/03/14 09:00 | Kai Lemstra v Bruno Santanna | 3-6,3-6 |
| ITF Croacia F2 | 2018/03/13 08:00 | Kai Lemstra v Valentin Royer | 1-6,6-4,6-3 |
| ITF Croacia F2 | 2018/03/11 08:00 | Kai Lemstra v Marco De Rosa | 6-2,6-3 |
| ITF Croacia F1 | 2018/03/07 09:00 | Anze Arh v Kai Lemstra | 7-5,6-1 |
| ITF Croacia F3 | 2018/03/21 12:20 | Deni Zmak v David Perez Sanz | 6-3,6-0 |
| ITF Croacia F3 | 2018/03/20 08:30 | Ivan Sabanov v Deni Zmak | 2-6,3-6 |
| ITF Croacia F3 | 2018/03/19 14:00 | Deni Zmak v Andres Gabriel Ciurletti | 6-2,6-2 |
| ITF Croacia F3 | 2018/03/19 11:00 | Andre Biro v Deni Zmak | 2-6,3-6 |
| ITF Croacia F2 | 2018/03/13 08:00 | Tom Kocevar-Desman v Deni Zmak | 6-3,3-6,6-4 |
| ITF Croacia F2 | 2018/03/11 08:00 | Marko Pavlovic v Deni Zmak | 0-6,1-6 |
| ITF Croacia F2 | 2018/03/10 08:00 | Dominik Kisantal v Deni Zmak | 1-6,2-6 |
| ITF Croacia F1 | 2018/03/08 09:00 | Alexandar Lazarov v Deni Zmak | 6-4,6-3 |