Stadium: Court 2 Round: 62 Ground: Clay
| ITF M25 Kottingbrunn | 2021/07/18 07:30 | Goldsteiner, Peter v Ondrej Valek | 6-2,6-2 |
| ITF M25 Telfs | 2021/07/13 07:30 | Goldsteiner, Peter v Bachmaier, Philip | 6-0,3-6,4-10 |
| ITF M25 Velenje | 2021/07/09 09:00 | Goldsteiner, Peter v Gonzalo Lama | 2-6,4-6 |
| ITF M25 Velenje | 2021/07/08 09:45 | Oscar Jose Gutierrez v Goldsteiner, Peter | 6-7,6-3,4-6 |
| ITF M25 Velenje | 2021/07/07 08:00 | Goldsteiner, Peter v Gal Emersic Potocnik | 6-1,6-0 |
| ITF M25 Velenje | 2021/07/06 10:10 | Goldsteiner, Peter v Heger, Tim | 6-1,6-4 |
| ITF M25 Velenje | 2021/07/05 16:20 | Goldsteiner, Peter v Roko Horvat | 7-6,6-4 |
| Sarajevo, Singles Main, M-ITF-BIH-05A | 2021/05/31 10:00 | Goldsteiner, Peter v Petar Jovanovic | 6-7,4-6 |
| ITF M25 Kottingbrunn | 2021/07/18 07:30 | Martin Zeljenka v Kis Balazs, Rafael | 2-6,6-4,10-2 |
| ITF M25 Belgrade | 2021/06/29 07:00 | Bogdan Pavel v Martin Zeljenka | 6-1,6-3 |
| ITF M25 Belgrade | 2021/06/28 10:00 | Martin Zeljenka v Minin, Matvey | 7-5,6-3 |
| ITF M25 Belgrade | 2021/06/27 12:00 | Martin Zeljenka v George Gregoriou | 6-1,6-1 |
| Sibenik, Singles M-ITF-CRO-05A | 2021/05/17 11:00 | Martin Zeljenka v Breysach , Martin | 6-7,3-6 |
| Sibenik, Singles M-ITF-CRO-05A | 2021/05/16 07:30 | Hoogland, Joris v Martin Zeljenka | 6-7,3-6 |
| ITF - M15 Prijedor | 2021/05/09 09:30 | Kristijan Juhas v Martin Zeljenka | 6-1,6-1 |
| Sibenik, Singles M-ITF-CRO-05A | 2021/04/19 12:20 | Gorazd Srbljak v Martin Zeljenka | 6-0,6-2 |