| ITF M25 Kiseljak | 05/30 10:55 | 25 | Nicolas Zanellato v Stefan Kostic | 6-1,6-1 | |
| ITF M15 Brcko | 05/23 10:00 | 25 | Stefan Kostic v Muang Thong United U19 | 0-6,1-6 | |
| ITF M15 Prijedor | 05/19 07:00 | 25 | Tim Ruehl v Stefan Kostic | 6-1,6-1 | |
| ITF M15 Doboj | 05/10 08:00 | 25 | Kirill Mishkin v Stefan Kostic | 6-2,1-6,6-1 | |
| ITF M15 Zlatibor | 09/11 09:45 | 62 | Stefan Kostic v Milos Vukovic | 0-6,3-6 |