| ITF France F18 | 09/05 07:30 | 25 | Ugo Humbert v Yannick Mertens | 6-3,6-2 | |
| Challenger Meerbusch | 08/15 15:15 | 25 | Karim-Mohamed Maamoun v Yannick Mertens | 6-3,6-2 | |
| ITF Germany F10 | 08/08 12:40 | 25 | Yannick Mertens v George Von Massow | 3-6,4-6 | |
| Challenger - Segovia | 08/01 08:00 | 25 | [245] Goncalo Oliveira v Yannick Mertens [286] | 6-3,3-6,6-4 | |
| ATP Gstaad Qual | 07/22 10:10 | 45 | [282] Yannick Mertens v Gleb Sakharov [191] | 4-6,5-7 | |
| Challenger Scheveningen | 07/18 11:40 | 25 | [336] Botic Van De Zandschulp v Yannick Mertens [282] | 4-6,6-3,6-2 | |
| ITF France F15 | 07/10 18:00 | 25 | Yannick Mertens v Edoardo Eremin | 5-7,2-6 | |
| Challenger Recanati | 07/05 15:30 | 26 | [276] Yannick Mertens v Quentin Halys [139] | 1-6,4-6 | |
| Challenger Recanati | 07/04 08:30 | 25 | [276] Yannick Mertens v Dmitry Popko [206] | 3-6,6-3,7-6 | |
| ATP Antalya Qual | 06/25 10:10 | 46 | [221] Ramkumar Ramanathan v Yannick Mertens [267] | 6-3,6-4 | |
| ATP Antalya Qual | 06/24 10:50 | 45 | [418] Altug Celikbilek v Yannick Mertens [267] | 2-6,4-6 | |
| ITF Turkey F23 | 06/13 07:00 | 25 | [454] Antoine Hoang v Yannick Mertens [268] | 6-4,6-3 | |
| Challenger Mestre | 05/23 08:00 | 25 | [320] Axel Michon v Yannick Mertens [272] | 6-4,6-7,7-5 | |
| ITF Romania F1 | 05/20 08:00 | 28 | Yannick Mertens v Sam Riffice | 6-3,5-7,4-6 | |
| ITF Romania F1 | 05/19 07:00 | 27 | Yannick Mertens v Gianni Ross | 2-6,6-3,6-4 | |
| ITF Romania F1 | 05/18 11:25 | 26 | Yannick Mertens v Calin Manda | 6-3,6-3 | |
| ITF Romania F1 | 05/16 09:10 | 25 | Yannick Mertens v Cristian Florentin Voinea | 6-3,6-4 | |
| ITF Italy F12 | 05/10 07:30 | 25 | Yannick Mertens v Lukas Ollert | 6-3,4-6,2-6 | |
| ATP Munich Qual | 04/30 09:00 | - | [265] Yannick Mertens v Guido Pella [158] | 3-6,4-6 | |
| ATP Munich Qual | 04/29 10:00 | - | [146] Alexander Bublik v Yannick Mertens [265] | 1-6,3-6 | |
| ITF USA F13 | 04/14 22:25 | 27 | [251] Yannick Mertens v Eric Quigley [401] | 6-2,3-6,4-6 | |
| ITF USA F13 | 04/13 17:00 | 26 | Yannick Mertens v Yibing Wu | 6-3,6-1 | |
| ITF USA F12 | 04/05 19:00 | 25 | Jan Choinski v Yannick Mertens | 4-6,6-4,6-1 | |
| ITF Portugal F4 | 04/01 09:30 | 28 | [250] Yannick Mertens v Hubert Hurkacz [359] | 6-7,4-6 | |
| ITF Portugal F4 | 03/31 11:20 | 27 | [250] Yannick Mertens v Fred Gil [433] | 6-3,6-2 | |
| ITF Portugal F4 | 03/30 12:05 | 26 | Yannick Mertens v Goncalo Falcao | 6-4,6-3 | |
| ITF Portugal F4 | 03/29 11:15 | 25 | [250] Yannick Mertens v Felipe Cunha Silva [394] | 6-4,6-0 | |
| ITF Portugal F3 | 03/17 10:30 | 26 | Eduardo Dischinger v Yannick Mertens | 6-4,7-6 | |
| ITF Portugal F3 | 03/15 11:00 | 25 | Billy Harris v Yannick Mertens | 2-6,4-6 | |
| ITF Portugal F2 | 03/12 15:00 | 29 | [242] Yannick Mertens v Lucas Miedler [403] | 6-4,6-2 |