Stadium: Center Court Round: 46 Ground: Carpet indoor
| Challenger Como | 2018/08/25 12:10 | Igor Sijsling v Facundo Arguello | 5-7,1-6 |
| Challenger Lexington | 2018/07/31 17:55 | Ronnie Schneider v Igor Sijsling | 6-2,6-4 |
| ITF Germany F5 | 2018/06/27 15:25 | Filip Bergevi v Igor Sijsling | 6-1,6-2 |
| ITF Germany F5 | 2018/06/25 09:00 | Igor Sijsling v Jannik Rother | 6-1,6-3 |
| ITF Germany F5 | 2018/06/25 08:00 | Igor Sijsling v Quentin Folliot | 6-2,6-4 |
| Challenger Loughborough Qual | 2018/05/21 12:20 | Igor Sijsling v Jurij Rodionov | 6-7,3-6 |
| Challenger Loughborough Qual | 2018/05/20 14:30 | Igor Sijsling v Peter Bothwell | 6-4,6-2 |
| Challenger Loughborough Qual | 2018/05/19 17:20 | Igor Sijsling v Julian Ocleppo | 6-4,6-7,6-1 |
| Challenger Ismaning | 2018/10/14 12:40 | Tobias Simon v Alexander Erler | 6-7,6-4,6-7 |
| Challenger Ismaning | 2018/10/13 17:10 | Evan Furness v Tobias Simon | 2-6,6-7 |
| Challenger Ortisei | 2018/10/09 08:30 | Tobias Simon v Ricardas Berankis | 6-7,4-6 |
| Challenger Ortisei | 2018/10/08 08:00 | Tobias Simon v Aldin Setkic | 7-6,6-7,7-6 |
| Challenger Ortisei | 2018/10/07 08:00 | Christopher Heyman v Tobias Simon | 3-6,6-7 |
| Challenger Ortisei | 2018/10/06 08:00 | Tobias Simon v Petro Orlando Fellin | 6-2,6-1 |
| Challenger Almaty 2 | 2018/09/29 09:20 | Khumoyun Sultanov v Tobias Simon | 7-6,6-4 |
| Challenger Orleans | 2018/09/26 09:00 | Tobias Simon v Lorenzo Sonego | 3-6,7-6,3-6 |