Stadium: Central Round: 25 Ground: Hardcourt outdoor
| ITF M25 Ajaccio | 2021/07/05 15:30 | Pierre Antoine Tailleu v Raphael Gomila | 6-1,6-1 |
| ITF M15 Monastir | 2021/06/06 10:00 | Sungbeen Sim v Pierre Antoine Tailleu | 6-3,7-6 |
| ITF M15 Monastir | 2021/04/22 08:30 | Pierre Antoine Tailleu v Jonathan Mridha | 0-6,1-6 |
| ITF M15 Monastir | 2021/04/20 09:00 | Pierre Antoine Tailleu v Tushar Sharma | 6-3,6-4 |
| ITF M15 Monastir | 2021/04/04 10:30 | Pierre Antoine Tailleu v Romain Faucon | 4-6,6-7 |
| ITF M25 Bakio | 2021/06/29 15:20 | Yannick Mertens v Christian Harrison | 2-6,6-3,4-6 |
| ITF M15 Marbella | 2021/05/30 09:00 | Diego F Flores v Yannick Mertens | 2-6,1-6 |
| ITF M15 Marbella | 2021/05/29 07:55 | Yannick Mertens v Nicolas Alvarez Varona | 1-6,7-5,6-3 |
| ITF M15 Marbella | 2021/05/28 10:25 | Alejandro Moro Canas v Yannick Mertens | 4-6,5-7 |
| ITF M15 Marbella | 2021/05/27 09:20 | Maxime Mora v Yannick Mertens | 5-7,0-6 |
| ITF M15 Marbella | 2021/05/25 09:00 | Francisco Andreu Garcia v Yannick Mertens | 6-7,1-6 |
| ITF M15 Troisdorf | 2021/05/14 11:00 | Yannick Mertens v Elmar Ejupovic | 2-6,1-6 |
| ITF M15 Troisdorf | 2021/05/13 09:00 | Yannick Mertens v Luke Johnson | 7-6,6-4 |