Stadium: Court 6 Round: 62 Ground: Hardcourt outdoor
| ITF M25 The Hague | 2021/06/27 08:00 | Dax Donders v Zachary Eisinga | 6-2,7-5 |
| ITF M25 Alkmaar | 2021/06/21 14:25 | Guillaume Dermiens v Zachary Eisinga | 4-6,7-5,13-11 |
| ITF M25 Alkmaar | 2021/06/20 12:30 | Lodewijk Weststrate v Zachary Eisinga | 2-6,1-6 |
| ITF M15 Cairo | 2021/05/04 08:00 | Zachary Eisinga v Martin Dimitrov | 1-6,6-7 |
| ITF M15 Cairo | 2021/05/03 08:00 | Zachary Eisinga v Ali Alshati | 3-6,6-0,10-8 |
| ITF M15 Cairo | 2021/04/28 10:00 | Zachary Eisinga v Shintaro Mochizuki | 4-6,2-6 |
| ITF M15 Cairo | 2021/04/19 10:30 | Zachary Eisinga v Fares Zakaria | 2-6,6-3,3-10 |
| ITF M15 Cairo | 2021/04/18 07:00 | Zachary Eisinga v Anton Magnusson | 6-2,4-6,10-2 |
| ITF M15 Shymkent | 2021/05/31 05:00 | Bogdan Seleznev v Saba Purtseladze | 2-6,1-6 |
| ITF M15 Shymkent | 2021/05/24 05:20 | Antonio Campo v Bogdan Seleznev | 6-0,6-1 |
| ITF M15 St Petersburg Qual | 2021/02/07 07:00 | Andrea Guerrieri v Bogdan Seleznev | 6-2,6-1 |
| ITF M15 St Petersburg | 2021/01/31 09:45 | Bogdan Seleznev v Mikhail Fufygin | 0-6,0-6 |