Round: 62 Ground: Clay
| Davis Cup | 2017/02/05 08:00 | Lloyd Harris v Mattias Siimar | 7-5,6-3 |
| ITF Egypt F2 | 2017/01/23 08:00 | Libor Salaba v Mattias Siimar | 7-6,6-3 |
| ITF Egypt F2 | 2017/01/22 10:30 | Mattias Siimar v Nicolas Uryson | 6-2,6-7,6-4 |
| ITF Estonia F3 | 2016/11/01 12:05 | Alexander Vasilenko v Mattias Siimar | 6-1,6-3 |
| ITF Estonia F2 | 2016/10/27 14:30 | Kenneth Raisma v Mattias Siimar | 6-1,6-4 |
| ITF Estonia F2 | 2016/10/24 13:00 | Verneri Tuomi v Mattias Siimar | 3-6,0-6 |
| ITF Estonia F1 | 2016/07/26 22:00 | Yann Wojcik v Mattias Siimar | 7-5,7-6 |
| ITF Estonia F1 | 2016/07/25 22:00 | Mattias Siimar v Karl Kiur Saar | 2-6,6-3,6-3 |
| ITF Estonia F3 | 2016/11/01 13:25 | Kristofer Siimar v Vladimir Ivanov | 0-6,4-6 |
| ITF Estonia F2 | 2016/10/24 15:00 | Dzmitry Zhyrmont v Kristofer Siimar | 6-0,6-0 |
| ITF Estonia F1 | 2015/11/09 08:00 | Vitaly Kozyukov v Kristofer Siimar | 6-2,6-3 |
| ITF Estonia F3 | 2015/11/03 15:00 | Kenneth Raisma v Kristofer Siimar | 6-2,6-0 |
| ITF Lithuania F1 | 2015/07/21 10:25 | Claudio Fortuna v Kristofer Siimar | 7-5,6-0 |
| ITF Estonia F2 | 2014/07/19 07:00 | Kristofer Siimar v Kirill Saplin | 5-7,1-6 |
| ITF Estonia F1 | 2014/07/13 07:00 | Julius Tverijonas v Kristofer Siimar | 4-6,6-4,6-2 |