Stadium: Court 2 Round: 25 Ground: Hardcourt outdoor
| Challenger Pozoblanco | 2021/07/22 16:00 | van Rijthoven, Tim v Igor Sijsling | 6-4,6-4 |
| Iasi, Romania | 2021/07/12 11:50 | Felipe Meligeni Rodrigues Alves v Igor Sijsling | 7-5,6-2 |
| Braunchsweig, Germany | 2021/07/04 10:10 | Igor Sijsling v Hidalgo, Diego | 3-6,6-3,4-6 |
| 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 Pozoblanco | 2021/07/21 17:10 | Gabashvili, Teimuraz v Altug Celikbilek | 7-5,3-6,4-6 |
| Challenger Pozoblanco | 2021/07/20 15:00 | Matteo Martineau v Gabashvili, Teimuraz | 4-6,6-1,4-6 |
| Iasi, Romania | 2021/07/13 08:55 | Gabashvili, Teimuraz v Lucas Miedler | 5-7,6-4,5-7 |
| Braunchsweig, Germany | 2021/07/06 10:30 | Marvin Moeller v Gabashvili, Teimuraz | 7-5,6-3 |
| Milan, Italy | 2021/06/22 10:55 | Giulio Zeppieri v Gabashvili, Teimuraz | 6-1,7-6 |
| Challenger Almaty | 2021/06/16 06:35 | Gabashvili, Teimuraz v Jesper De Jong | 3-6,2-6 |
| Challenger Almaty | 2021/06/08 10:20 | Gabashvili, Teimuraz v Filip Cristian Jianu | 1-6,3-6 |
| ATP Parma | 2021/05/23 10:00 | Raul Brancaccio v Gabashvili, Teimuraz | 6-3,6-3 |