Stadium: Court 3 Round: 25 Ground: Hardcourt outdoor
| Challenger Banja Luka | 2021/09/10 16:00 | Marko Topo v Tomas Martin Etcheverry | 3-6,6-7 |
| Challenger Banja Luka | 2021/09/09 11:55 | Marko Topo v Vitaliy Sachko | 6-1,3-6,7-6 |
| Challenger Banja Luka | 2021/09/07 14:30 | Danilo Petrovic v Marko Topo | 6-4,6-7,2-6 |
| ITF M15 Allershausen | 2021/09/01 14:35 | Marko Topo v Tim Handel | 5-7,5-7 |
| ITF M15 Bad Waltersdorf | 2021/08/26 07:00 | Marko Topo v Gabriel Decamps | 4-6,5-7 |
| ITF M15 Bad Waltersdorf | 2021/08/24 07:00 | Dominik Boehler v Marko Topo | 7-6,6-7,4-6 |
| ATP Belgrade | 2021/05/23 13:00 | Marko Topo v Federico Coria | 6-4,2-6,0-6 |
| Challenger Belgrade | 2021/04/11 13:05 | Alessandro Giannessi v Marko Topo | 2-6,7-6,6-2 |
| ITF M15 St Petersburg | 2021/04/14 07:00 | Maxim Ratniuk v Marat Deviatiarov | 7-6,6-7,6-7 |
| ITF M15 St Petersburg | 2021/04/08 07:00 | Maxim Ratniuk v Artem Dubrivnyy | 2-6,1-6 |
| ITF M15 St Petersburg | 2021/04/05 08:30 | Maxim Ratniuk v Timur Kiyamov | 6-4,6-7,12-10 |
| ITF M15 St Petersburg | 2021/04/04 07:00 | Maxim Ratniuk v Maksim Starostin | 6-4,6-0 |
| ITF M15 Kazan | 2021/03/11 08:00 | Alexandr Binda v Maxim Ratniuk | 4-6,6-3,6-4 |
| ITF M15 Kazan | 2021/03/10 13:40 | Maxim Ratniuk v Alexander Zhurbin | 6-0,6-3 |
| ITF M15 St Petersburg | 2021/02/10 06:50 | Artem Dubrivnyy v Maxim Ratniuk | 6-2,6-3 |
| ITF M15 St Petersburg | 2021/02/08 10:05 | Maxim Ratniuk v Evgeny Philippov | 6-3,6-3 |