Stadium: Center Court Round: 45
| Challenger Caltanissetta | 2018/06/12 08:00 | Marcelo Arevalo v Marc Sieber | 1-6,6-1,7-5 |
| Challenger Caltanissetta Qual | 2018/06/11 10:15 | Joao Souza v Marc Sieber | 6-2,3-6,4-6 |
| Challenger Caltanissetta Qual | 2018/06/10 11:30 | Marc Sieber v Pawel Juszczak | 6-0,6-1 |
| Challenger Caltanissetta Qual | 2018/06/09 13:25 | Mikhail Balmashev v Marc Sieber | 0-6,1-6 |
| Challenger Prostejov Qual | 2018/06/03 15:25 | Marc Sieber v Jan Satral | 6-4,3-6,4-6 |
| Challenger Prostejov Qual | 2018/06/03 09:45 | Pavel Nejedly v Marc Sieber | 1-6,5-7 |
| ITF Hungary F2 | 2018/05/18 08:00 | Mate Valkusz v Marc Sieber | 6-1,6-1 |
| ITF Hungary F2 | 2018/05/17 14:55 | Emil Ruusuvuori v Marc Sieber | 2-6,3-6 |
| Challenger Marburg | 2018/07/06 14:00 | Hugo Dellien v Julian Lenz | 6-3,6-3 |
| Challenger Marburg | 2018/07/05 13:10 | Elliot Benchetrit v Julian Lenz | 4-6,5-7 |
| Challenger Marburg | 2018/07/04 16:45 | Julian Lenz v Rudolf Molleker | 3-6,6-3,7-6 |
| Challenger Marburg | 2018/07/02 14:00 | Sebastian Ofner v Julian Lenz | 1-6,6-7 |
| Challenger Heilbronn Qual | 2018/05/14 11:55 | Daniel Masur v Julian Lenz | 4-6,6-0,6-1 |
| Challenger Heilbronn Qual | 2018/05/13 13:00 | Julian Lenz v Adelchi Virgili | 6-3,6-2 |
| Challenger Heilbronn Qual | 2018/05/12 12:00 | Andrei Iakovlev v Julian Lenz | 0-6,0-6 |
| Challenger Ostrava Qual | 2018/04/28 10:40 | Julian Lenz v Juan Ignacio Galarza | 6-3,5-7,3-6 |