Stadium: Center Court Round: 46 Ground: Carpet indoor
| Meerbusch, Allemagne, Qualifications | 2018/08/13 09:00 | Tristan Lamasine v Sieber, Marc | 6-7,5-7 |
| Challenger Ismaning | 2018/10/13 09:00 | Tristan Lamasine v Lemstra, Sven | 6-3,6-4 |
| Challenger Tashkent | 2018/10/08 05:30 | Felix Auger Aliassime v Tristan Lamasine | 7-6,6-2 |
| Challenger Tashkent | 2018/10/07 05:00 | Sergey Fomin v Tristan Lamasine | 3-6,4-6 |
| Challenger Tashkent | 2018/10/06 05:00 | Saidkarimov, Saida' Lo v Tristan Lamasine | 4-6,3-6 |
| Challenger Almaty 2 | 2018/09/29 04:00 | Tristan Lamasine v Margaroli, Luca | 6-3,3-6,4-6 |
| Challenger Kaohsiung | 2018/09/17 04:15 | Yunseong Chung v Tristan Lamasine | 6-4,6-2 |
| Challenger Kaohsiung | 2018/09/16 08:25 | Tristan Lamasine v Mousley, Bradley | 6-3,7-5 |
| Challenger Kaohsiung | 2018/09/15 10:35 | Jacopo Berrettini v Tristan Lamasine | 2-6,5-7 |
| Challenger Ismaning | 2018/10/13 10:25 | Kern, Robin v Sieber, Marc | 3-6,2-6 |
| Challenger Ortisei | 2018/10/06 13:30 | Sieber, Marc v Albano Olivetti | 6-4,6-7,4-6 |
| ITF Germany F14 | 2018/10/04 15:05 | Francesco Ferrari v Sieber, Marc | 2-6,6-4,6-3 |
| ITF Germany F14 | 2018/10/02 10:00 | Max Wiskandt v Sieber, Marc | 2-6,0-6 |
| ITF Germany F14 | 2018/10/01 10:00 | Sieber, Marc v von Der Schulenburg, Henry | 6-1,6-2 |
| ITF Germany F14 | 2018/09/30 11:30 | Sieber, Marc v Nystroem, Patrick | 6-1,7-5 |
| Challenger Sibiu Qual | 2018/09/16 12:00 | Frunza, Nicolae v Sieber, Marc | 6-4,6-3 |
| Challenger Seville | 2018/09/01 16:00 | Sieber, Marc v Bernabe Zapata Miralles | 6-7,3-6 |