Stadium: Center Court Round: 19 Ground: Clay
| Challenger Salzburg | 2021/07/04 11:10 | Yosuke Watanuki v Jeroen Vanneste | 3-6,2-6 |
| Challenger Prostejov | 2021/06/14 08:30 | Alex Rybakov v Jeroen Vanneste | 7-6,7-6 |
| Challenger Prostejov | 2021/06/13 11:25 | Adam Jurajda v Jeroen Vanneste | 6-4,6-7,1-6 |
| ITF M15 Antalya | 2021/05/05 08:25 | Jeroen Vanneste v Yanki Erel | 7-6,5-7,5-7 |
| ITF M15 Antalya | 2021/05/02 09:20 | Sandro Ehrat v Jeroen Vanneste | 4-6,3-6 |
| ITF M15 Antalya | 2021/05/01 07:30 | Peter Heller v Jeroen Vanneste | 3-6,3-6 |
| ITF M15 Antalya | 2021/04/30 07:15 | Oleksii Krutykh v Jeroen Vanneste | 4-6,6-1,1-6 |
| ITF M15 Antalya | 2021/04/29 10:10 | Jacopo Berrettini v Jeroen Vanneste | 4-6,0-6 |
| Challenger Salzburg | 2021/07/04 09:15 | Sadio Doumbia v Alexander Erler | 6-7,5-7 |
| ITF M25 Klosters | 2021/06/24 07:00 | Alexander Erler v Nicolas Moreno De Alboran | 1-6,5-7 |
| ITF M25 Klosters | 2021/06/23 07:00 | Alexander Erler v Yannik Steinegger | 6-7,6-2,6-1 |
| Challenger Prostejov | 2021/06/16 10:05 | Dalibor Svrcina v Alexander Erler | 6-1,7-5 |
| Challenger Prostejov | 2021/06/14 08:30 | Alexander Erler v Pavel Nejedly | 7-5,6-3 |
| Challenger Prostejov | 2021/06/13 11:10 | Alexander Erler v Jakub Mensik | 6-3,6-4 |
| ITF M25 Most | 2021/05/27 07:55 | Alexander Erler v Franco Agamenone | 4-6,0-6 |
| ITF M25 Most | 2021/05/25 09:35 | Alexander Erler v Jean Thirouin | 7-5,7-6 |