Stadium: Court 7 Round: 14 Ground: Clay
| Challenger Forli | 2021/06/16 11:15 | Mats Moraing v Igor Sijsling | 3-6,6-4,6-2 |
| Challenger Forli | 2021/06/14 15:40 | Igor Sijsling v Andrea Pellegrino | 6-2,7-6 |
| Challenger Nottingham | 2021/06/07 12:10 | Aleksandar Vukic v Igor Sijsling | 6-4,7-6 |
| Challenger Nottingham | 2021/06/06 18:30 | Igor Sijsling v Matteo Viola | 6-7,6-1,6-0 |
| Challenger Oeiras | 2021/05/25 11:30 | Igor Sijsling v Timofey Skatov | 6-2,2-6,6-7 |
| Challenger Rome | 2021/04/27 09:30 | Danilo Petrovic v Igor Sijsling | 6-1,7-6 |
| Challenger Rome | 2021/04/26 11:15 | Zizou Bergs v Igor Sijsling | 6-7,1-6 |
| Challenger Rome Qual | 2021/04/25 11:05 | Igor Sijsling v Alexey Vatutin | 6-3,6-0 |
| 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 |
| Challenger Salinas 2 | 2021/04/27 16:15 | Adrian Menendez-Maceiras v Diego Hidalgo | 7-5,6-0 |
| Challenger Salinas | 2021/04/20 15:50 | Diego Hidalgo v Nicolas Mejia | 3-6,6-1,5-7 |