Stadium: Court 2 Round: 25 Ground: Hardcourt indoor
| ITF M15 East Lansing | 2019/11/20 21:15 | Cannon Kingsley v Siimar, Mattias | 7-5,6-2 |
| ITF M15 Helsinki | 2019/08/20 08:30 | Siimar, Mattias v Rikkonen, Roni | 5-7,6-0,9-11 |
| ITF M15 Helsinki | 2019/08/19 10:00 | Siimar, Mattias v Vanko, Tomas | 6-1,6-0 |
| ITF M15 Parnu | 2019/07/15 07:00 | Siimar, Mattias v Tadas Babelis | 6-2,3-6,13-15 |
| ITF Finland F2 | 2018/08/08 12:55 | Siimar, Mattias v Hansson, Gustav | 2-6,2-6 |
| ITF Finland F2 | 2018/08/06 08:00 | Siim Troost v Siimar, Mattias | 6-2,1-6,0-6 |
| ITF Finland F1 | 2018/08/02 11:00 | Siimar, Mattias v Niklas-Salminen, Patrick | 4-6,6-7 |
| ITF Finland F1 | 2018/08/01 09:35 | Pontico, Hugo v Siimar, Mattias | 4-6,4-6 |
| ITF M15 Parnu | 2020/11/02 11:00 | Hietaranta, Roni Mikael v Burdet, Adrien | 5-7,6-2,13-11 |
| ITF M15 Parnu | 2019/10/30 12:25 | Muscheites, Lasse v Hietaranta, Roni Mikael | 6-4,6-1 |
| ITF M15 Parnu | 2019/10/29 08:00 | Hietaranta, Roni Mikael v Mansson, Marcus | 2-6,7-6,10-4 |
| Pajulahti, Singles M-ITF-FIN-02A | 2019/09/18 12:30 | Yanki Erel v Hietaranta, Roni Mikael | 6-0,6-2 |
| ITF M15 Helsinki | 2019/08/22 08:00 | Hietaranta, Roni Mikael v Juan Manuel Cerundolo | 2-6,2-6 |
| ITF M15 Helsinki | 2019/08/21 13:30 | Hietaranta, Roni Mikael v Sarpola, Masi | 6-4,6-3 |
| ITF M15 Parnu | 2019/07/18 08:45 | Goldsteiner, Peter v Hietaranta, Roni Mikael | 6-1,7-5 |
| ITF M15 Parnu | 2019/07/15 13:00 | Grinvalds, Roberts v Hietaranta, Roni Mikael | 2-6,6-0,7-10 |