Round: 62 Ground: Clay
| ITF Italy F16 Qual | 2017/06/04 13:05 | Wilson Leite v Mattias Siimar | 6-4,6-0 |
| ITF Italy F16 Qual | 2017/06/03 08:30 | Paolo Dagnino v Mattias Siimar | 2-6,3-6 |
| Davis Cup | 2017/04/09 09:00 | Mattias Siimar v Lucas Catarina | 4-6,6-4,6-7 |
| 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 Poland F1 | 2017/06/11 08:00 | Kristofer Siimar v Linus Frost | 1-6,6-3,0-6 |
| Davis Cup | 2017/04/09 11:10 | Kristofer Siimar v Thomas Oger | 4-6,4-6 |
| 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 |