Stadium: Court 10 Round: 26 Ground: Clay
| Challenger Kyiv | 2021/09/07 14:50 | Clement Tabur v Ergi Kirkin | 4-6,6-7 |
| ITF M25 Ueberlingen | 2021/08/22 12:00 | Ergi Kirkin v Henri Squire | 6-3,4-6,6-4 |
| ITF M25 Ueberlingen | 2021/08/21 10:00 | Ergi Kirkin v Tim Handel | 4-6,7-6,7-6 |
| ITF M25 Ueberlingen | 2021/08/20 10:00 | Ergi Kirkin v Oliver Crawford | 6-4,3-6,6-2 |
| ITF M25 Ueberlingen | 2021/08/19 12:30 | Ergi Kirkin v Leopold Zima | 5-7,6-0,6-3 |
| ITF M25 Ueberlingen | 2021/08/17 14:50 | Ergi Kirkin v Manfred Fellin | 1-6,6-0,6-2 |
| ITF M15 Parnu | 2021/08/08 08:00 | Ergi Kirkin v Mattias Siimar | 5-7,6-3,6-3 |
| ITF M15 Parnu | 2021/08/07 09:30 | Ergi Kirkin v Simone Roncalli | 6-1,6-2 |
| Challenger Kyiv | 2021/09/07 13:20 | Jelle Sels v Sergiy Stakhovsky | 2-6,3-6 |
| US Open | 2021/08/24 22:55 | Zane Khan v Sergiy Stakhovsky | 4-6,7-5,6-3 |
| Challenger Nur-Sultan | 2021/07/21 06:30 | Nick Chappell v Sergiy Stakhovsky | 7-6,6-4 |
| Challenger Nur-Sultan | 2021/07/20 07:20 | Benjamin Lock v Sergiy Stakhovsky | 3-6,6-3,5-7 |
| Challenger Nur-Sultan | 2021/07/15 06:00 | Sergiy Stakhovsky v Jason Kubler | 2-6,6-3,2-6 |
| Challenger Nur-Sultan | 2021/07/13 06:10 | Sergiy Stakhovsky v Pavel Kotov | 7-5,6-2 |
| Challenger Porto | 2021/07/03 10:00 | Altug Celikbilek v Sergiy Stakhovsky | 6-2,6-1 |
| Challenger Porto | 2021/07/02 12:00 | Goncalo Oliveira v Sergiy Stakhovsky | 6-7,6-7 |