Stadium: Court 2 Round: 26 Ground: Carpet indoor
| Challenger Banja Luka | 2021/09/07 08:00 | David Poljak v Tomas Martin Etcheverry | 2-6,5-7 |
| Challenger Banja Luka | 2021/09/06 11:35 | David Poljak v Mircea-Alexandru Jecan | 6-3,6-4 |
| Challenger Banja Luka | 2021/09/05 12:25 | David Poljak v Moez Echargui | 2-6,6-3,6-2 |
| Challenger Warsaw | 2021/08/22 12:15 | Jonathan Mridha v David Poljak | 2-6,6-4,6-2 |
| ITF M25 Prostejov | 2021/08/17 09:00 | Alex Rybakov v David Poljak | 7-6,7-6 |
| ITF M25 Grodzisk Mazowiecki | 2021/08/08 08:00 | David Poljak v Zsombor Piros | 4-6,6-7 |
| ITF M25 Grodzisk Mazowiecki | 2021/08/07 11:55 | David Poljak v Adam Pavlasek | 4-6,7-6,6-1 |
| ITF M25 Grodzisk Mazowiecki | 2021/08/07 07:25 | David Poljak v Michal Dembek | 6-3,3-6,6-3 |
| ITF M25 Ricany | 2021/08/29 08:00 | Ondrej Horak v Lambert Ruland | 1-6,1-6 |
| ITF M15 Bad Waltersdorf | 2021/08/23 09:00 | Ondrej Horak v Alessandro Ragazzi | 3-6,6-4,4-10 |
| ITF M15 Warmbad-Villach | 2021/08/17 08:00 | Philip Bachmaier v Ondrej Horak | 6-2,6-0 |
| ITF M15 Warmbad-Villach | 2021/08/16 12:30 | Leonardo Chiari v Ondrej Horak | 3-6,2-6 |
| ITF M15 Telavi | 2021/08/03 07:25 | Yanki Erel v Ondrej Horak | 6-1,6-4 |
| ITF M25 Telavi | 2021/07/27 07:20 | Ondrej Horak v Alexander Boborykin | 2-6,6-3,5-10 |
| ITF M25 Telavi | 2021/07/26 13:10 | Petr Bar Biryukov v Ondrej Horak | 4-6,2-6 |
| ITF M25 Telfs | 2021/07/16 10:00 | Kirill Kivattsev v Ondrej Horak | 6-2,6-2 |