| UTR Pro Tennis Series Pazardzhik Women | 2021/05/11 10:00 | Shkumbova, Mirela v 코스토바, 엘리트사 | 0-6,1-6 |
| UTR Pro Tennis Series Pazardzhik Women | 2021/05/06 10:00 | Shkumbova, Mirela v 코스토바, 엘리트사 | 1-6,0-6 |
| UTR Pro Tennis Series Plovdiv Women | 2021/12/13 12:00 | Mariya Vyshkina v Shkumbova, Mirela | 1-6,3-6 |
| ITF W15 Sozopol | 2021/09/14 07:00 | Cirpanli, Defne v Shkumbova, Mirela | 6-1,6-1 |
| ITF W15 Sozopol | 2021/09/13 10:30 | Ekaterina Kuznetsova v Shkumbova, Mirela | 5-7,4-6 |
| ITF Women Varna | 2021/09/05 05:30 | 그보즈데노비치, 사라 v Shkumbova, Mirela | 4-6,6-2,10-7 |
| UTR Pro Tennis Series Sofia Women | 2021/09/01 08:00 | Shkumbova, Mirela v Peeva, Stela | 1-6,4-6 |
| UTR Pro Tennis Series Sofia Women | 2021/08/31 09:30 | Shkumbova, Mirela v 코랄, 나스티아 | 2-6,6-2,1-5 |
| UTR Pro Tennis Series Sofia Women | 2021/08/29 13:30 | 라덴코비치, 마자 v Shkumbova, Mirela | 6-3,4-6,5-2 |
| UTR Pro Tennis Series Pazardzhik Women | 2021/05/13 06:00 | Shkumbova, Mirela v Ruseva, Nikol | 6-4,5-2 |
| UTR Pro Tennis Series Barcelona Women | 2021/11/07 12:20 | 코스토바, 엘리트사 v 즐로초바, 주자나 | 3-6,5-7 |
| UTR Pro Tennis Series Barcelona Women | 2021/11/06 09:30 | 코스토바, 엘리트사 v 란티구아 데 라 누에즈, 아나 | 6-0,6-1 |
| UTR Pro Tennis Series Barcelona Women | 2021/11/05 15:15 | 코스토바, 엘리트사 v Valeria Avdeeva | 6-1,6-2 |
| UTR Pro Tennis Series Barcelona Women | 2021/11/04 11:30 | 코스토바, 엘리트사 v 우그렐리드즈, 니나 | 4-6,6-1,6-0 |
| UTR Pro Tennis Series Barcelona Women | 2021/11/03 10:00 | 클팩, 아구스티나 v 코스토바, 엘리트사 | 3-6,0-6 |
| UTR Pro Tennis Series Barcelona Women | 2021/11/02 12:30 | Lucia Aranda Arcas v 코스토바, 엘리트사 | 6-4,4-6,1-5 |
| WTA Belgrade | 2021/07/27 14:50 | 코스토바, 엘리트사 v 루스, 아란트사 | 1-6,0-6 |
| ITF W60 Biarritz | 2021/07/14 09:30 | 코스토바, 엘리트사 v 카시노, 에스텔 | 4-6,3-6 |