Round: 62 Ground: Clay
| ITF M15 Kottingbrunn | 2023/08/13 10:30 | Victor Sklenka v Thomas Zych | 6-4,6-1 |
| ITF M15 Warmbad-Villach | 2023/05/23 11:55 | Thomas Zych v Nik Mikovic | 2-6,1-6 |
| ITF M15 Caslano | 2023/08/20 11:35 | Francesco Liucci v Jakub Ostajewski | 6-3,6-3 |
| ITF M15 Uberlingen | 2023/08/14 12:30 | Gregor Ramskogler v Jakub Ostajewski | 6-4,6-1 |
| ITF M25 Lodz | 2023/08/07 13:30 | Francesco Ferrari v Jakub Ostajewski | 6-3,6-3 |
| ITF M25 Edwardsville | 2023/07/24 14:00 | Jakub Ostajewski v Bjorn Swenson | 4-6,2-6 |
| ITF M25 Santo Domingo | 2023/06/18 14:00 | Jakub Ostajewski v Maxime St-Hilaire | 1-6,0-6 |
| ITF M25 Jablonec Nad Nisou | 2023/05/28 11:30 | Tomas Zlatohlavek v Jakub Ostajewski | 6-3,6-1 |
| ITF M15 Warmbad-Villach | 2023/05/21 10:00 | Jakub Ostajewski v Jimmy Yang | 4-6,5-7 |
| ITF M15 Warmbad-Villach | 2023/05/21 07:00 | Jakub Ostajewski v Zan M Mihovec | 6-0,6-0 |