Stadium: WSG Grandstand Round: 25 Ground: Clay
| Meerbusch, Allemagne, Qualifications | 2018/08/13 09:00 | Tristan Lamasine v Sieber, Marc | 6-7,5-7 |
| Meerbusch, Allemagne, Qualifications | 2018/08/12 09:40 | Sieber, Marc v Adrian Oetzbach | 6-0,6-0 |
| Meerbusch, Allemagne, Qualifications | 2018/08/11 11:45 | Mats Rosenkranz v Sieber, Marc | 3-6,3-6 |
| Challenger Pullach Qual | 2018/08/04 09:00 | Sieber, Marc v Lenz, Julian | 4-6,6-4,4-6 |
| Challenger Liberec Qual | 2018/07/29 08:30 | Sieber, Marc v Marvin Moeller | 2-6,5-7 |
| Challenger Liberec Qual | 2018/07/28 08:00 | Juan Pablo Ficovich v Sieber, Marc | 3-6,6-3,3-6 |
| Challenger - Prague | 2018/07/24 11:30 | Nedovyesov, Aleksandr v Sieber, Marc | 6-0,6-4 |
| Challenger Prague Qual | 2018/07/23 10:10 | Torebko, Peter v Sieber, Marc | 1-6,4-6 |
| Challenger Liberec | 2018/08/03 11:00 | Sousa, Pedro v Tatlot, Johan Sebastien | 6-3,6-1 |
| Challenger Liberec | 2018/08/01 11:30 | Tatlot, Johan Sebastien v Satral, Jan | 6-3,5-7,6-0 |
| Challenger Liberec | 2018/07/31 08:00 | Tatlot, Johan Sebastien v Steven Diez | 6-3,6-2 |
| Challenger San Benedetto | 2018/07/18 17:00 | Tatlot, Johan Sebastien v Daniel Elahi Galan | 3-6,4-6 |
| Challenger San Benedetto | 2018/07/17 13:05 | Tatlot, Johan Sebastien v Andrea Collarini | 6-1,6-7,6-3 |
| Challenger Bastad | 2018/07/10 10:35 | Lukas Rosol v Tatlot, Johan Sebastien | 6-3,6-2 |
| Lyon, France | 2018/06/17 12:30 | Felix Auger Aliassime v Tatlot, Johan Sebastien | 6-7,7-5,6-2 |
| Lyon, France | 2018/06/16 13:40 | Tatlot, Johan Sebastien v Marcora, Roberto | 7-6,6-2 |