Stadium: Court 1 Round: 25 Ground: Hardcourt indoor
| ITF M15 Selva Gardena | 2021/10/25 08:30 | Kai Lemstra v Dominique Graf | 7-5,6-2 |
| ITF M15 Selva Gardena | 2021/10/24 10:45 | Kai Lemstra v Davide Ferrarolli | 6-4,6-3 |
| ITF M25 Hamburg | 2021/10/17 07:55 | Tom Schonenberg v Kai Lemstra | 6-2,6-2 |
| ITF M15 Monastir | 2021/08/26 07:30 | Kai Lemstra v Renta Tokuda | 2-6,2-6 |
| ITF M15 Monastir | 2021/08/25 07:30 | Hamzeh Al-Aswad v Kai Lemstra | 2-6,1-6 |
| ITF M15 Monastir | 2021/08/24 07:30 | Seita Watanabe v Kai Lemstra | 1-6,1-6 |
| ITF M15 Monastir | 2021/08/23 09:00 | Alec Beckley v Kai Lemstra | 3-6,2-6 |
| ITF M15 Monastir | 2021/08/22 12:00 | Lucca Pinto v Kai Lemstra | 3-6,0-6 |
| ITF M15 Selva Gardena | 2021/10/25 10:35 | Nicolo Pozzani v Carlo Alberto Fossati | 5-7,7-6,3-10 |
| ITF M15 Selva Gardena | 2021/10/24 14:05 | Giacomo Crisostomo v Carlo Alberto Fossati | 4-6,1-6 |
| ITF M25 Caslano | 2021/08/24 07:30 | Stefano Baldoni v Carlo Alberto Fossati | 6-2,6-3 |
| ITF M25 Caslano | 2021/08/23 08:00 | Alexander Wolfschmidt v Carlo Alberto Fossati | 6-7,3-6 |
| ITF M15 Monastir | 2021/07/25 12:00 | Carlo Alberto Fossati v Joshua Sheehy | 4-6,3-6 |
| ITF M15 Monastir | 2021/07/19 08:00 | Maxence Beauge v Carlo Alberto Fossati | 7-5,6-1 |
| ITF M15 Monastir | 2021/07/18 08:00 | Francisco Faigenbaum v Carlo Alberto Fossati | 1-6,2-6 |
| ITF M25 Casinalbo | 2021/07/04 13:00 | Gabriel Roveri Sidney v Carlo Alberto Fossati | 7-5,7-6 |