Stadium: Hard 1 Round: 26 Ground: Hardcourt outdoor
| ITF Greece F5 | 2018/03/28 06:00 | Kalovelonis, Markos v Stergiou, Ioannis | 3-6,2-6 |
| ITF Greece F7 | 2018/11/06 09:10 | Stergiou, Ioannis v Stefan Palosi | 6-4,7-5 |
| ITF Greece F6 | 2018/10/30 10:55 | Stergiou, Ioannis v Rapp, Austin | 5-7,5-7 |
| ITF Italy F20 Qual | 2018/07/22 13:00 | Stergiou, Ioannis v Capello, Ettore | 6-7,5-7 |
| ITF Italy F20 Qual | 2018/07/21 07:30 | Stergiou, Ioannis v Elio Jose Ribeiro Lago | 4-6,6-2,6-4 |
| ITF Italy F19 | 2018/07/16 19:00 | Tomas Martin Etcheverry v Stergiou, Ioannis | 6-2,7-6 |
| ITF Bosnia and Herzegovina F2 | 2018/05/25 08:00 | Nerman Fatic v Stergiou, Ioannis | 6-4,6-0 |
| ITF Bosnia and Herzegovina F2 | 2018/05/24 11:35 | Stergiou, Ioannis v Kalenichenko, Danylo | 6-1,7-6 |
| ITF Bosnia and Herzegovina F2 | 2018/05/23 12:30 | Jandric, Darko v Stergiou, Ioannis | 0-6,3-6 |
| ITF Greece F7 | 2018/11/06 11:15 | Hersey, Jake v Kalovelonis, Markos | 6-7,3-6 |
| ITF Greece F6 | 2018/11/01 10:30 | Elbaz, Shahar v Kalovelonis, Markos | 7-5,6-1 |
| ITF Greece F6 | 2018/10/31 09:00 | Kapiris, Stamatis v Kalovelonis, Markos | 3-6,2-6 |
| ITF Lebanon F2 | 2018/10/02 13:00 | Hady Habib v Kalovelonis, Markos | 6-1,6-7,6-3 |
| ITF Lebanon F1 | 2018/09/27 13:00 | Reboul, Fabien v Kalovelonis, Markos | 6-2,6-7,6-1 |
| ITF Lebanon F1 | 2018/09/25 13:00 | Kalovelonis, Markos v Luca Tomasetto | 6-3,6-2 |
| Egypt F18, Singles Qualifying | 2018/09/13 07:30 | Krivokuca, Neven v Kalovelonis, Markos | 6-4,6-0 |
| ITF Russia F7 | 2018/08/23 07:00 | Kalovelonis, Markos v Kravchuk, Konstantin | 2-6,2-6 |