Stadion: Sparkassen Court Round: 25 Ground: Clay
| ITF - M25 - Bolton | 2019/04/04 09:00 | Ryan Nijboer v Julian Lenz | 3-6,6-7 |
| Challenger - Mailand | 2021/06/22 08:30 | Julian Lenz v Duje Ajdukovic | 1-6,2-6 |
| Challenger - Forlì | 2021/06/14 12:30 | Julian Lenz v Quentin Halys | 3-6,3-6 |
| Challenger - Oeiras | 2021/05/26 10:00 | Holger Rune v Julian Lenz | 5-7,6-4,6-3 |
| Challenger - Oeiras | 2021/05/24 14:05 | Corentin Denolly v Julian Lenz | 4-6,0-6 |
| Challenger - Biella | 2021/05/16 11:00 | Julian Lenz v Francesco Passaro | 6-7,1-6 |
| ITF - M25 - Biel | 2021/03/30 13:20 | Jelle Sels v Julian Lenz | 7-5,6-4 |
| Challenger - Lugano | 2021/03/22 17:50 | Yuichi Sugita v Julian Lenz | 6-2,7-5 |
| Challenger - Biella | 2021/03/09 10:20 | Liam Broady v Julian Lenz | 7-6,6-4 |
| ITF - M25 - Den Haag | 2021/06/30 12:55 | Mateus Alves v Ryan Nijboer | 7-6,6-3 |
| ITF - M25 - Alkmaar | 2021/06/24 12:00 | Marko Tepavac v Ryan Nijboer | 4-6,7-6,6-1 |
| ITF - M15 - Skopje | 2021/06/10 11:30 | Miljan Zekic v Ryan Nijboer | 6-2,6-3 |
| ITF - M15 - Skopje | 2021/06/10 07:45 | Ryan Nijboer v Dian Nedev | 6-3,6-2 |
| ITF - M15 - Skopje | 2021/06/06 07:55 | Alexis Gautier v Ryan Nijboer | 6-2,3-6,6-2 |
| ITF - M15 - Skopje | 2021/06/05 10:40 | Dalibor Svrcina v Ryan Nijboer | 6-1,4-6,5-7 |
| ITF - M15 - Skopje | 2021/06/04 10:25 | Alexander Weis v Ryan Nijboer | 6-7,6-7 |
| ITF - M15 - Skopje | 2021/06/03 09:30 | Ryan Nijboer v Alex Rybakov | 2-6,7-6,6-4 |