Stadium: TSITSIPAS COURT Round: 62 Ground: Hardcourt outdoor
| ITF M25 Most | 2021/05/26 10:15 | Antoine Escoffier v Kai Lemstra | 6-3,7-5 |
| ITF M25 Most | 2021/05/25 10:15 | Kai Lemstra v Edward Hubner | 6-1,6-1 |
| ITF M25 Most | 2021/05/24 08:00 | Kai Lemstra v Niklas Rohrer | 6-3,6-2 |
| ITF M25 Most | 2021/05/23 14:00 | Kai Lemstra v Vojtech Petr | 6-4,6-4 |
| ITF M25 Jablonec Nad Nisou | 2021/05/18 07:30 | Andrew Paulson v Kai Lemstra | 6-3,6-4 |
| ITF M25 Jablonec Nad Nisou | 2021/05/17 07:30 | Jan Jermar v Kai Lemstra | 4-6,4-6 |
| ITF M25 Jablonec Nad Nisou | 2021/05/16 08:30 | Matyas Cerny v Kai Lemstra | 3-6,3-6 |
| ITF M25 Meerbusch | 2021/04/12 09:30 | Marvin Netuschil v Kai Lemstra | 6-2,6-3 |
| UTR Pro Tennis Series Atlanta | 2021/04/16 17:00 | Drew Van Orderlain v Ronan Jachuck | 3-6,3-6 |
| UTR Pro Tennis Series Atlanta | 2021/04/15 16:30 | Drew Van Orderlain v Matthias Haim | 5-7,3-6 |
| UTR Pro Tennis Series Atlanta | 2021/04/14 16:30 | Evan Bynoe v Drew Van Orderlain | 6-4,6-1 |
| UTR Pro Tennis Series Atlanta | 2021/04/13 14:30 | McClain Kessler v Drew Van Orderlain | 6-4,5-1 |
| UTR Pro Tennis Series Cancun | 2021/04/11 13:00 | Evan Bynoe v Drew Van Orderlain | 7-6,5-3 |
| UTR Pro Tennis Series Cancun | 2021/04/10 14:30 | Drew Van Orderlain v Gabriel Evans | 7-6,6-2 |
| UTR Pro Tennis Series Cancun | 2021/04/09 17:00 | Drew Van Orderlain v Quang Duong | 6-0,5-2 |
| UTR Pro Tennis Series Cancun | 2021/04/07 17:00 | Drew Van Orderlain v Luciano Doria | 6-3,5-7,2-6 |