Stadium: Centre Court Round: 26 Ground: Clay
| Challenger - Praha | 2021/08/23 13:40 | Filip Cristian Jianu v Matheus P De Almeida | 6-7,2-6 |
| Challenger - Verona | 2021/08/18 13:00 | Holger Rune v Matheus P De Almeida | 6-2,6-3 |
| Challenger - Verona | 2021/08/17 08:30 | Malek Jaziri v Matheus P De Almeida | 4-6,1-6 |
| Challenger - Verona | 2021/08/16 11:00 | Thiago Agustin Tirante v Matheus P De Almeida | 3-6,6-3,5-7 |
| Challenger - Verona | 2021/08/15 11:10 | Nicolas Alvarez v Matheus P De Almeida | 2-6,1-6 |
| Challenger - Todi | 2021/07/17 16:35 | Matheus P De Almeida v Mario Vilella Martinez | 6-7,6-3,1-6 |
| Challenger - Todi | 2021/07/16 13:00 | Nicolas Jarry v Matheus P De Almeida | 6-3,3-6,1-6 |
| Challenger - Todi | 2021/07/14 13:00 | Matheus P De Almeida v Dmitry Popko | 3-6,6-1,6-2 |
| Challenger - Praha | 2021/08/24 13:45 | Daniel Siniakov v Igor Sijsling | 4-6,3-6 |
| Challenger - Segovia | 2021/07/27 14:25 | Igor Sijsling v Teymuraz Gabashvili | 1-6,3-6 |
| Challenger - Pozoblanco | 2021/07/22 16:00 | Tim Van Rijthoven v Igor Sijsling | 6-4,6-4 |
| Challenger - Iasi | 2021/07/12 11:50 | Felipe Meligeni Rodrigues Alves v Igor Sijsling | 7-5,6-2 |
| Challenger - Braunschweig | 2021/07/04 10:10 | Igor Sijsling v Diego Hidalgo | 3-6,6-3,4-6 |
| 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 |