| ATP - Rio De Janeiro | 02/18 21:20 | 25 | [109] Mayer, Leonardo v Lorenzo Sonego [52] | 1-6,7-5,4-6 | |
| ATP - Buenos Aires | 02/12 00:30 | 25 | [107] Mayer, Leonardo v Albert Ramos-Vinolas [42] | 6-4,3-6,5-7 | |
| ATP - Cordoba | 02/05 00:05 | 25 | [103] Mayer, Leonardo v Jaume Munar [87] | 4-6,3-6 | |
| Open d'Australie | 01/21 01:45 | 23 | [101] Mayer, Leonardo v Tommy Paul [80] | 6-4,4-6,4-6,4-6 | |
| ATP - Auckland | 01/14 03:30 | 25 | [100] Mayer, Leonardo v Marco Cecchinato [76] | 6-7,7-6,6-7 | |
| ATP - Auckland | 01/11 22:00 | 164 | [87] Thiago Monteiro v Mayer, Leonardo [88] | 7-6,4-6,6-1 | |
| ATP - Auckland | 01/10 22:00 | 64 | [400] Purcell, Rhett v Mayer, Leonardo [88] | 5-7,6-4,1-6 | |
| Challenger Guayaquil | 11/01 23:00 | 27 | [155] Varillas, Juan Pablo v Mayer, Leonardo [94] | Retired | |
| Challenger Guayaquil | 11/01 00:35 | 26 | [268] Quiroz, Roberto v Mayer, Leonardo [94] | 3-6,4-6 | |
| Challenger Guayaquil | 10/29 21:00 | 25 | [204] Andrea Collarini v Mayer, Leonardo [94] | 1-6,6-2,4-6 | |
| Challenger Lima | 10/24 19:30 | 26 | [201] Joao Menezes v Mayer, Leonardo [95] | 6-4,1-6,6-4 | |
| Challenger Lima | 10/22 23:10 | 25 | [405] Cervantes, Inigo v Mayer, Leonardo [95] | 2-6,3-6 | |
| Santo Domingo, Dominican Republic | 10/10 02:50 | 25 | [368] Clezar, Guilherme v Mayer, Leonardo [94] | 6-3,1-6,7-6 | |
| Challenger Campinas | 10/03 22:10 | 26 | Bellucci, Thomaz v Mayer, Leonardo | Walkover | |
| Challenger Campinas | 10/01 20:10 | 25 | [427] Camilo Ugo Carabelli v Mayer, Leonardo [97] | 6-7,4-6 | |
| Challenger - Buenos Aires | 09/28 15:20 | 28 | [166] Facundo Bagnis v Mayer, Leonardo [100] | 6-2,3-6,6-3 | |
| Challenger - Buenos Aires | 09/27 22:25 | 27 | [100] Mayer, Leonardo v Juan P Ficovich [352] | 6-1,6-7,7-6 | |
| Challenger - Buenos Aires | 09/26 21:30 | 26 | Mayer, Leonardo v Diaz Acosta, Facundo | 7-6,6-3 | |
| Challenger - Buenos Aires | 09/25 20:30 | 25 | [100] Mayer, Leonardo v Federico Zeballos [258] | 7-5,6-1 | |
| US Open, New York, USA | 08/27 22:00 | 23 | [104] Antoine Hoang v Mayer, Leonardo [95] | 3-6,6-2,6-7,6-1,6-3 | |
| Kitzbuhel, Austria | 07/30 09:00 | 25 | [75] Andujar, Pablo v Mayer, Leonardo [81] | 3-6,6-3,6-2 | |
| Hamburg, Germany | 07/22 16:30 | 25 | [51] Mayer, Leonardo v Rudolf Molleker [150] | 6-7,4-6 | |
| Umag, Croatia | 07/19 15:30 | 27 | [32] Laslo Djere v Mayer, Leonardo [60] | 6-4,6-7,6-3 | |
| Umag, Croatia | 07/17 15:15 | 26 | [142] Jiri Vesely v Mayer, Leonardo [60] | 6-3,4-6,4-6 | |
| Umag, Croatia | 07/16 17:30 | 25 | [79] Andujar, Pablo v Mayer, Leonardo [60] | 1-6,5-7 | |
| Wimbledon, London, Great Britain | 07/03 11:25 | 24 | [59] Mayer, Leonardo v Hubert Hurkacz [48] | 7-6,1-6,6-7,3-6 | |
| Wimbledon, London, Great Britain | 07/01 11:25 | 23 | [92] Gulbis, Ernests v Mayer, Leonardo [59] | 1-6,6-7,2-6 | |
| Eastbourne, Great Britain | 06/25 10:00 | 25 | Jay Clarke v Mayer, Leonardo | Cancelled | |
| Open de France | 06/02 11:30 | 26 | [68] Mayer, Leonardo v Federer, Roger [3] | 2-6,3-6,3-6 | |
| Open de France | 05/31 13:30 | 25 | [252] Mahut, Nicolas v Mayer, Leonardo [68] | 6-3,6-7,4-6,6-7 |