Stadium: Court 7 Round: 14 Ground: Clay
| Forli 6, Italy | 2021/06/16 11:15 | Moraing, Mats v Igor Sijsling | 3-6,6-4,6-2 |
| Forli 6, Italy | 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 Viola, Matteo | 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 | Petrovic, Danilo 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 |
| Tulsa, Singles Main, M-ITF-USA-16A | 2021/06/17 14:00 | Nicolas Kicker v Hidalgo, Diego | 6-4,7-5 |
| Tulsa, Singles Main, M-ITF-USA-16A | 2021/06/16 17:10 | Strong Kirchheimer v Hidalgo, Diego | 7-6,2-6,3-6 |
| ITF - M25 Santo Domingo | 2021/06/10 12:50 | Evan Zhu v Hidalgo, Diego | 6-2,6-3 |
| ITF - M25 Santo Domingo | 2021/06/09 13:00 | El Midhawy, Adam v Hidalgo, Diego | 4-6,6-7 |
| ITF - M25 Santo Domingo | 2021/06/03 15:55 | Seelig, Kyle v Hidalgo, Diego | 6-2,6-4 |
| ITF - M25 Santo Domingo | 2021/06/01 15:55 | Lopez Villasenor, Gerardo v Hidalgo, Diego | 6-4,3-6,3-6 |
| Challenger Salinas 2 | 2021/04/27 16:15 | Menendez-Maceiras, Adrian v Hidalgo, Diego | 7-5,6-0 |
| Challenger Salinas | 2021/04/20 15:50 | Hidalgo, Diego v Nicolas Mejia | 3-6,6-1,5-7 |