| ITF Egypt F1 | 01/19 08:00 | 27 | Smirnov, Artem v Mertens, Yannick | 7-6,1-6,4-6 | |
| ITF Egypt F1 | 01/18 08:00 | 26 | Moez Echargui v Mertens, Yannick | 1-6,2-6 | |
| ITF Egypt F1 | 01/16 08:00 | 25 | Fabian Marozsan v Mertens, Yannick | 3-6,6-7 | |
| Bangkok, Thaïlande | 01/09 07:20 | 25 | Emil Ruusuvuori v Mertens, Yannick | 6-4,3-6,7-5 | |
| ITF Israel F16 | 12/03 08:00 | 29 | [268] Edan Leshem v Mertens, Yannick [302] | 6-7,3-6 | |
| ITF Israel F16 | 12/02 08:30 | 28 | [302] Mertens, Yannick v Viola, Matteo [287] | 6-2,6-2 | |
| ITF Israel F16 | 12/01 09:00 | 27 | Pauwels, Maxime v Mertens, Yannick | 2-6,2-6 | |
| ITF Israel F16 | 11/30 08:00 | 26 | Constantin B Kouzmine v Mertens, Yannick | 1-6,3-6 | |
| ITF Israel F16 | 11/29 10:15 | 25 | Ugo Blanchet v Mertens, Yannick | 2-6,2-6 | |
| ITF Israel F15 | 11/04 10:55 | 29 | [415] Jankovits, Yannick v Mertens, Yannick [321] | 7-5,7-6 | |
| ITF Israel F15 Qual | 11/03 09:50 | 28 | Heyman, Christopher v Mertens, Yannick | 6-7,6-3,2-6 | |
| ITF Israel F15 | 11/03 08:00 | - | [365] Heyman, Christopher v Mertens, Yannick [321] | 6-7,6-3,2-5 | |
| ITF Israel F15 | 11/02 11:15 | 27 | [464] Okala, Jules v Mertens, Yannick [321] | 5-7,0-6 | |
| ITF Israel F15 | 11/01 08:00 | 26 | Elbaz, Shahar v Mertens, Yannick | 2-6,3-6 | |
| ITF Israel F15 | 10/31 10:50 | 25 | Vladyslav Orlov v Mertens, Yannick | 3-6,2-6 | |
| France F24, Singles | 10/17 08:30 | 25 | [482] Okala, Jules v Mertens, Yannick [329] | 2-6,7-5,6-4 | |
| ITF Germany F14 | 10/12 10:00 | 26 | Griekspoor, Scott v Mertens, Yannick | 6-3,6-3 | |
| ITF Germany F14 | 10/10 11:50 | 25 | Ouvrard, Victor v Mertens, Yannick | 1-6,2-6 | |
| ITF Germany F14 | 10/09 10:00 | 44 | Mertens, Yannick v Martinez, Mirko | 6-2,6-1 | |
| ITF Germany F14 | 10/08 11:30 | 44 | Mertens, Yannick v Bangratz, Johannes | 6-1,6-1 | |
| ITF Portugal F20 | 09/30 10:00 | 29 | [333] Mertens, Yannick v Krstin, Pedja [302] | 3-6,7-6,6-2 | |
| ITF Portugal F20 | 09/29 12:45 | 28 | [277] Monteiro, Joao v Mertens, Yannick [333] | 4-6,6-4,4-6 | |
| ITF Portugal F20 | 09/28 12:10 | 27 | [301] Daniel Masur v Mertens, Yannick [333] | 2-6,6-7 | |
| ITF Portugal F20 | 09/27 11:25 | 26 | [426] Hubert Hurkacz v Mertens, Yannick [333] | 4-6,1-6 | |
| ITF Portugal F20 | 09/26 09:00 | 25 | [389] Kanar, Jonathan v Mertens, Yannick [333] | 3-6,0-6 | |
| ATP Metz Qual | 09/18 11:30 | 46 | [95] Gojowczyk, Peter v Mertens, Yannick [339] | 6-3,6-4 | |
| ATP Metz Qual | 09/17 13:50 | 45 | [331] Mertens, Yannick v Calvin Hemery [179] | 7-5,6-1 | |
| Istanbul, Turkey | 09/12 11:15 | 25 | [175] Mirza Basic v Mertens, Yannick [331] | 3-6,6-3,7-5 | |
| Challenger Istanbul Qual | 09/10 08:00 | 54 | Mertens, Yannick v Dzhanashia, Shalva | 6-1,6-2 | |
| Challenger Istanbul Qual | 09/09 09:25 | 46 | Mertens, Yannick v Strokan, Artem | 6-0,6-0 |