Stadium: Van Mossel Kia Court Round: 14 Ground: Clay
| ITF M25 Marburg | 2021/07/05 12:05 | Yan Sabanin v Guy Den Ouden | 7-6,6-4 |
| ITF M25 The Hague | 2021/06/28 10:15 | Guy Den Ouden v Henri Squire | 2-6,0-6 |
| ITF M25 Alkmaar | 2021/06/23 10:35 | Deney Wassermann v Guy Den Ouden | 7-6,7-5 |
| ITF M15 Sharm El Sheikh | 2020/11/19 10:10 | Guy Den Ouden v Miljan Zekic | 6-7,6-7 |
| ITF M15 Sharm El Sheikh | 2020/11/18 12:45 | Juan Bautista Otegui v Guy Den Ouden | 6-1,3-6,4-6 |
| ITF M15 Sharm El Sheikh | 2020/11/11 08:00 | Guy Den Ouden v Jeffrey Von Der Schulenburg | 2-6,5-7 |
| ITF M15 Sharm El Sheikh | 2020/11/04 08:00 | Guy Den Ouden v Sidharth Rawat | 5-7,6-7 |
| ITF M15 Alkmaar | 2020/08/24 08:00 | Robert Strombachs v Guy Den Ouden | 6-3,6-1 |
| Challenger Braunschweig | 2021/07/05 09:30 | Diego Hidalgo v Dayne Kelly | 3-6,7-6,3-6 |
| Challenger Braunschweig | 2021/07/04 10:10 | Igor Sijsling v Diego Hidalgo | 3-6,6-3,4-6 |
| ITF M25 Tulsa | 2021/06/17 14:00 | Nicolas Kicker v Diego Hidalgo | 6-4,7-5 |
| ITF M25 Tulsa | 2021/06/16 17:10 | Strong Kirchheimer v Diego Hidalgo | 7-6,2-6,3-6 |
| ITF M25 Santo Domingo | 2021/06/10 12:50 | Evan Zhu v Diego Hidalgo | 6-2,6-3 |
| ITF M25 Santo Domingo | 2021/06/09 13:00 | Adam El Mihdawy v Diego Hidalgo | 4-6,6-7 |
| ITF M25 Santo Domingo | 2021/06/03 15:55 | Kyle Seelig v Diego Hidalgo | 6-2,6-4 |
| ITF M25 Santo Domingo | 2021/06/01 15:55 | Gerardo L Villasenor v Diego Hidalgo | 6-4,3-6,3-6 |