Stadium: M.A.R.A - Court Round: 45
| ITF Germany F1 | 2018/01/07 11:30 | Heger, Tim v Kai Lemstra | 4-6,4-6 |
| ITF M15 Kaarst | 2019/02/04 08:30 | Heger, Tim v Klimov, Philipp | 6-2,6-4 |
| ITF - M25 Nussloch | 2019/01/22 11:00 | Simon, Tobias v Heger, Tim | 6-3,6-4 |
| ITF Czech Republic F12 | 2018/11/26 09:00 | Heger, Tim v Sprlak Puk, Albert | 3-6,4-6 |
| ITF Greece F8 | 2018/11/15 09:40 | Pervolarakis, Michail v Heger, Tim | 6-2,6-2 |
| ITF Greece F8 | 2018/11/13 13:25 | Heger, Tim v Solberg, Christoffer | 7-6,6-1 |
| ITF Estonia F3 | 2018/11/06 09:00 | Tyurnev, Evgeny v Heger, Tim | 6-3,3-6,6-1 |
| ITF Estonia F3 | 2018/11/04 12:00 | Heger, Tim v Parko, Carl Bret | 6-3,6-3 |
| ITF Estonia F3 | 2018/11/03 14:00 | Heger, Tim v Mandma, Alexander Georg | 6-4,6-0 |
| Challenger - Koblenz | 2019/01/15 09:00 | Torebko, Peter v Kai Lemstra | 6-1,1-6,6-1 |
| ITF - M15 Monastir | 2019/01/10 10:00 | Kai Lemstra v Jonathan Mridha | 1-6,6-3,2-6 |
| ITF - M15 Monastir | 2019/01/09 11:45 | Seraphim, Christian v Kai Lemstra | 4-6,4-6 |
| ITF Czech Republic F12 | 2018/11/27 09:00 | Remy Bertola v Kai Lemstra | 6-4,6-3 |
| ITF Czech Republic F12 | 2018/11/26 09:00 | Juras, David v Kai Lemstra | 6-4,3-6,6-7 |
| Czech Republic F11, Singles Qualifying | 2018/11/19 11:00 | Marek, Wojciech v Kai Lemstra | 3-6,6-3,7-5 |
| Challenger Eckental | 2018/10/27 17:00 | Kai Lemstra v Satral, Jan | 5-7,1-6 |
| ITF Czech Republic F7 | 2018/10/23 11:10 | Kai Lemstra v Piotr Grynkowski | 4-6,6-1,4-6 |