Stadion: Bernard Frances Round: 28 Ground: Hardcourt outdoor
| 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 |
| ITF - M15 - Troisdorf | 2021/05/12 12:00 | Yannick Mertens v Max Wiskandt | 7-6,6-3 |
| ITF - M15 - Sibenik | 2021/04/21 12:05 | Gergely Madarasz v Yannick Mertens | 6-4,5-7,6-3 |
| ITF - M25 - Meerbusch | 2021/04/15 10:00 | Alexander Erler v Yannick Mertens | 6-3,3-6,6-1 |
| ITF - M15 - Marbella | 2021/05/28 08:00 | Nicolas Alvarez Varona v Imanol L Morillo | 6-2,4-6,6-4 |
| ITF - M15 - Marbella | 2021/05/27 09:00 | Nicolas Alvarez Varona v Max Alcala Gurri | 6-4,6-1 |
| ITF - M15 - Marbella | 2021/05/26 13:55 | Nicolas Alvarez Varona v Luis Diego Chavez Villalpando | 6-2,6-1 |
| ITF - M15 - Valldoreix | 2021/05/12 12:05 | Alex M Pujolras v Nicolas Alvarez Varona | 6-7,6-2,6-1 |
| ITF - M15 - Valldoreix | 2021/05/11 08:00 | Nicolas Alvarez Varona v Oleg Prihodko | 6-7,6-4,11-9 |
| ITF - M15 - Valldoreix | 2021/05/10 08:00 | Nicolas Alvarez Varona v Axel Garcian | 6-1,6-4 |
| ITF - M15 - Valldoreix | 2021/05/09 12:00 | Nicolas Alvarez Varona v Luigi Castelletti | 6-2,7-6 |
| ITF - M15 - Majadahonda | 2021/05/06 10:30 | Pedro Vives Marcos v Nicolas Alvarez Varona | 6-3,6-7,6-4 |