Stadium: Court 1 Round: 26 Ground: Clay
| Challenger St. Petersburg MD | 2021/03/11 11:00 | Sijsling/Smits v Kravchuk/Yevseyev | 2-6,4-6 |
| Challenger St. Petersburg MD | 2021/03/10 10:00 | Gabashvili/Nedovyesov v Sijsling/Smits | 1-6,6-3,4-10 |
| Challenger Cherbourg MD | 2021/02/11 14:45 | Sijsling/Smits v Klein/Molcan | 6-7,6-7 |
| Challenger Cherbourg MD | 2021/02/09 14:45 | Drzewiecki/Jebavy v Sijsling/Smits | 6-1,6-7,7-10 |
| ITF M15 Bressuire MD | 2021/01/19 14:55 | de Schepper/Napolitano v Sijsling/Smits | 7-6,6-7,10-5 |
| ITF M15 Antalya MD | 2021/01/09 11:45 | Sijsling/Smits v Harris/Sabanin | 6-0,3-6,13-15 |
| ITF M15 Antalya MD | 2021/01/09 08:35 | Sijsling/Smits v Deschamps/Savelev | 6-2,7-5 |
| ITF M25 Rodez MD | 2020/10/16 14:30 | Doumbia/Reboul v Sijsling/Smits | 6-3,7-5 |