Stadium: Court 3 Round: 14 Ground: Hardcourt indoor
| ITF M15 Troisdorf | 2021/05/14 11:00 | Yannick Mertens v Elmar Ejupovic | 2-6,1-6 |
| ITF M25 Plaisir | 2021/09/16 07:50 | Yannick Mertens v Tristan Schoolkate | 4-6,6-7 |
| ITF M25 Plaisir | 2021/09/15 09:35 | Yannick Mertens v Paul Cayre | 6-4,6-1 |
| ITF M25 Sintra | 2021/09/08 12:25 | Yannick Mertens v Felix Corwin | 7-6,3-6,4-6 |
| ITF M25 Bagneres-De-Bigorre | 2021/09/01 11:40 | Yannick Mertens v Titouan Droguet | 2-6,6-2,3-6 |
| ITF M25 Koksijde | 2021/08/17 16:20 | Yannick Mertens v Arnaud Bovy | 7-5,1-6,5-7 |
| ITF M25 Frankfurt am Main | 2021/08/11 14:00 | Yannick Mertens v Daniel Cukierman | 3-6,3-6 |
| ITF M25 Ajaccio | 2021/07/08 07:00 | Loris Pourroy v Yannick Mertens | 6-1,4-6,6-3 |
| ITF M25 Ajaccio | 2021/07/07 10:00 | Pierre Antoine Tailleu v Yannick Mertens | 4-6,4-6 |
| Challenger Istanbul | 2021/09/13 09:00 | Aldin Setkic v Elmar Ejupovic | 7-6,6-7,6-3 |
| Challenger Istanbul | 2021/09/12 11:05 | Togan Tokac v Elmar Ejupovic | 2-6,4-6 |
| Challenger Banja Luka | 2021/09/06 09:00 | Elmar Ejupovic v Jonathan Mridha | 6-2,2-6,2-6 |
| Challenger Banja Luka | 2021/09/05 11:15 | Elmar Ejupovic v Andrej Nedic | 3-6,6-3,6-0 |
| Challenger Prague | 2021/08/23 08:00 | Uladzimir Ignatik v Elmar Ejupovic | 7-6,2-6,6-4 |
| Challenger Prague | 2021/08/22 11:35 | Jiri Jenicek v Elmar Ejupovic | 2-6,1-6 |
| Challenger San Marino | 2021/08/08 08:00 | Elmar Ejupovic v Francesco Forti | 1-6,4-6 |
| ITF M25 Bolzano | 2021/08/04 09:00 | Elmar Ejupovic v Matteo Arnaldi | 4-6,6-7 |