| Country (sports) | |
|---|---|
| Residence | Tallinn, Estonia | 
| Born | 3 February 1998 Tallinn, Estonia  | 
| Plays | Left-handed (two handed-backhand) | 
| Prize money | $8,305 | 
| Singles | |
| Career record | 0–3 (at ATP Tour level and Grand Slam level) | 
| Career titles | 0 | 
| Highest ranking | No. 1,036 (25 October 2021) | 
| Grand Slam singles results | |
| Australian Open Junior | 2R (2016) | 
| Wimbledon Junior | 1R (2016) | 
| US Open Junior | 1R (2015) | 
| Doubles | |
| Career record | 2–3 (at ATP Tour level and Grand Slam level) | 
| Highest ranking | No. 826 (8 November 2021) | 
| Grand Slam doubles results | |
| Australian Open Junior | QF (2016) | 
| US Open Junior | 2R (2015) | 
| Team competitions | |
| Davis Cup | 5–6 | 
| Last updated on: 11 July 2022. | |
Mattias Siimar (born 3 February 1998) is an Estonian tennis player. [1]
Siimar has a career high ATP singles ranking of 1036, achieved on 25 October 2021.
Playing for Estonia in Davis Cup, Siimar has a win–loss record of 5–6. His twin brother Kristofer Siimar is also a tennis player.
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| Result | W–L | Date | Tournament | Tier | Surface | Opponent | Score | 
|---|---|---|---|---|---|---|---|
| Loss | 0–1 | Aug 2021 | M15 Pärnu, Estonia | World Tennis Tour | Clay |   | 7–5, 3–6, 3–6 | 
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| Rubber outcome | No. | Rubber | Match type (partner if any) | Opponent nation | Opponent player(s) | Score | 
|---|---|---|---|---|---|---|
| Victory | 1 | III | Doubles (with Kenneth Raisma) (dead rubber) |   | Rrezart Cungu / Ivan Saveljić | 6–1, 6–2 | 
| Victory | 2 | III | Doubles (with Jürgen Zopp) (dead rubber) |   | Granit Bajraliu / Gurash Hasani | 6–1, 6–1 | 
| Victory | 3 | III | Doubles (with Jürgen Zopp) (dead rubber) |   | Christos Antonopoulos / Vasileios Iliopoulos | 6–0, 6–1 | 
| Defeat | 4 | III | Doubles (with Kenneth Raisma) |   | Raven Klaasen / Ruan Roelofse | 7–6(7–4), 3–6, 4–6, 5–7 | 
| Defeat | 5 | IV | Singles (dead rubber) | Lloyd Harris | 5–7, 3–6 | |
| Victory | 6 | III | Doubles (with Kenneth Raisma) |   | Romain Arneodo / Benjamin Balleret | 4–6, 6–1, 6–2, 7–6(9–7) | 
| Defeat | 7 | IV | Singles (dead rubber) | Lucas Catarina | 4–6, 6–4, 6–7(3–7) | |
| Defeat | 8 | III | Doubles (with Kenneth Raisma) |   | Ričardas Berankis / Laurynas Grigelis | 6–2, 4–6, 6–7(4–7) | 
| Victory | 9 | III | Doubles (with Vladimir Ivanov) |   | Aleksandre Metreveli / George Tsivadze | 3–6, 6–3, 6–3 | 
| Defeat | 10 | II | Singles |   | Henri Laaksonen | 4–6, 0–6 | 
| Defeat | 11 | III | Doubles (with Vladimir Ivanov) | Marc-Andrea Hüsler / Dominic Stricker | 4–6, 6–7(4–7) | |