Stadion: Court 4 Round: 25 Ground: Hardcourt outdoor
| Challenger - St. Petersburg | 2021/03/08 07:00 | Khumoyun Sultanov v Tim Van Rijthoven | 2-6,1-6 |
| Challenger - St. Petersburg - Qualifikation | 2021/03/07 09:35 | Khumoyun Sultanov v Daniil Glinka | 7-6,6-4 |
| Challenger - St. Petersburg | 2021/03/01 13:25 | Altug Celikbilek v Khumoyun Sultanov | 6-4,6-1 |
| ITF - M15 - Antalya | 2021/02/12 10:30 | Khumoyun Sultanov v Filip Cristian Jianu | 2-6,1-6 |
| ITF - M15 - Antalya | 2021/02/11 09:20 | Khumoyun Sultanov v Alvaro Lopez San Martin | 6-2,6-3 |
| ITF - M15 - Antalya | 2021/02/10 07:00 | Khumoyun Sultanov v Gabriele Maria Noce | 6-7,6-3,7-6 |
| ITF - M15 - Antalya | 2021/02/05 07:00 | Khumoyun Sultanov v Hamad Medjedovic | 5-7,6-4,2-6 |
| ITF - M15 - Antalya | 2021/02/04 09:55 | Khumoyun Sultanov v Timo Legout | 6-3,0-6,6-3 |
| ITF - M15 - Monastir | 2021/05/10 12:30 | Robert Strombachs v Uisung Park | 3-6,6-7 |
| ITF - M15 - Monastir | 2021/05/10 08:00 | Robert Strombachs v Romain Faucon | 7-5,6-3 |
| ITF - M15 - Monastir | 2021/05/09 08:00 | Robert Strombachs v Lucio Carnevalle | 6-4,6-0 |
| ITF - M15 - Monastir | 2021/05/04 10:30 | Robert Strombachs v Yusuke Takahashi | 3-6,6-3,1-6 |
| ITF - M15 - Monastir | 2021/04/13 08:30 | Sho Shimabukuro v Robert Strombachs | 6-3,6-2 |
| ITF - M15 - Monastir | 2021/04/09 08:30 | Antoine Escoffier v Robert Strombachs | 6-1,6-4 |
| ITF - M15 - Monastir | 2021/04/08 09:50 | Buvaysar Gadamauri v Robert Strombachs | 1-6,2-6 |
| ITF - M15 - Monastir | 2021/04/07 10:10 | Robert Strombachs v Alexander Shevchenko | 1-6,6-3,7-5 |