Stadium: Court 4 Round: 14 Ground: Hardcourt indoor
| 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 |
| Challenger Belgrade | 2021/04/11 13:20 | Igor Sijsling v Marco Trungelliti | 3-6,3-6 |
| Challenger Oeiras | 2021/04/02 12:00 | Marco Trungelliti v Igor Sijsling | 6-3,6-4 |
| Challenger Oeiras | 2021/03/31 10:00 | Igor Sijsling v Gian Marco Moroni | 6-2,6-2 |
| Challenger Oeiras | 2021/03/30 09:00 | Manuel Guinard v Igor Sijsling | 1-6,5-7 |
| ATP Parma | 2021/05/23 12:55 | Mikael Ymer v Matteo Viola | 6-4,3-6,6-0 |
| ATP Parma | 2021/05/22 12:50 | Evgeny Karlovskiy v Matteo Viola | 5-7,7-5,5-7 |
| Challenger Biella | 2021/05/17 14:55 | Matteo Viola v Alexandre Muller | 6-4,3-6,1-6 |
| Challenger Zagreb | 2021/05/09 11:10 | Emilio Gomez v Matteo Viola | 7-5,6-7,6-1 |
| Challenger Biella | 2021/05/03 08:30 | Maximilian Marterer v Matteo Viola | 6-3,7-5 |
| Challenger Rome | 2021/04/18 13:25 | Matteo Viola v Alexey Vatutin | 3-6,7-6,1-6 |
| Challenger Split | 2021/04/12 08:30 | Zdenek Kolar v Matteo Viola | 6-2,6-4 |
| Challenger Split Qual | 2021/04/11 09:00 | Evgeny Karlovskiy v Matteo Viola | 2-6,2-6 |