| Hamburg, Germany | 07/30 13:00 | 29 | [138] Mayer, Leonardo v Mayer, Florian (1983) [101] | 6-4,4-6,6-3 | |
| Hamburg, Germany | 07/29 10:00 | 28 | [138] Mayer, Leonardo v Delbonis, Federico [81] | 6-3,7-5 | |
| Hamburg, Germany | 07/28 11:40 | 27 | [138] Mayer, Leonardo v Jiri Vesely [55] | 7-6,6-3 | |
| Hamburg, Germany | 07/27 16:15 | 26 | [138] Mayer, Leonardo v Jan-Lennard Struff [54] | 6-2,7-5 | |
| Hamburg, Germany | 07/25 17:00 | 25 | [24] Albert Ramos-Vinolas v Mayer, Leonardo [138] | 7-6,3-6,6-7 | |
| ATP Hamburg Qual | 07/23 12:40 | 46 | Rudolf Molleker v Mayer, Leonardo | 7-6,3-6,6-3 | |
| ATP Hamburg Qual | 07/22 13:50 | 45 | Louis Wessels v Mayer, Leonardo | 3-6,2-6 | |
| ATP Bastad | 07/18 11:40 | 25 | [89] Dolgopolov, Aleksandr v Mayer, Leonardo [134] | 6-3,6-2 | |
| ATP Bastad Qual | 07/17 14:15 | 46 | [166] Mathieu, Paul-Henri v Mayer, Leonardo [134] | 6-2,3-6,2-6 | |
| ATP Bastad Qual | 07/17 09:00 | 45 | [225] Tristan Lamasine v Mayer, Leonardo [134] | 6-7,7-6,2-6 | |
| Challenger Bastad | 07/15 11:00 | 29 | [79] Dusan Lajovic v Mayer, Leonardo [152] | 6-2,7-6 | |
| Challenger Bastad | 07/14 10:55 | 28 | [152] Mayer, Leonardo v Ymer, Mikael [398] | 6-3,6-0 | |
| Challenger Bastad | 07/13 09:00 | 27 | [152] Mayer, Leonardo v Laaksonen, Henri [104] | 3-6,6-3,6-2 | |
| Challenger Bastad | 07/12 11:55 | 26 | [152] Mayer, Leonardo v Filip Krajinovic [180] | 7-6,6-3 | |
| Challenger Bastad | 07/10 11:00 | 25 | [111] Casper Ruud v Mayer, Leonardo [152] | 6-3,6-7,4-6 | |
| Challenger Vicenza | 06/01 13:30 | 26 | [154] Mayer, Leonardo v Donati, Matteo [231] | 6-3,1-6,2-6 | |
| Challenger Vicenza | 05/30 11:50 | 25 | [154] Mayer, Leonardo v Cervantes, Inigo [163] | 6-4,7-6 | |
| French Open Qual | 05/24 10:30 | 45 | [151] Opelka, Reilly v Mayer, Leonardo [154] | 5-7,7-6,6-3 | |
| French Open Qual | 05/22 10:15 | 44 | [154] Mayer, Leonardo v Souza, Joao Olavo [140] | 6-2,6-1 | |
| Challenger - Savannah | 05/02 14:00 | 25 | [148] Mayer, Leonardo v Christopher O'Connell [255] | 6-4,5-7,1-6 | |
| Challenger - Tallahassee | 04/26 15:00 | 26 | [131] Mayer, Leonardo v Rola, Blaz [271] | 2-6,4-6 | |
| Challenger - Tallahassee | 04/25 14:00 | 25 | [131] Mayer, Leonardo v Statham, Rubin [399] | 6-4,6-2 | |
| Challenger - Tallahassee | 04/25 14:00 | 25 | Mayer, Leonardo v Aziz Dougaz | Cancelled | |
| Challenger - Sarasota | 04/17 17:20 | 25 | [112] Pavlasek, Adam v Mayer, Leonardo [132] | 1-6,7-5,6-4 | |
| ATP - Houston | 04/13 17:00 | 26 | [144] Mayer, Leonardo v Isner, John [23] | 7-6,6-7,3-6 | |
| ATP - Houston | 04/12 19:05 | 25 | [144] Mayer, Leonardo v Pavlasek, Adam [98] | 5-7,6-2,6-1 | |
| ATP Houston Qual | 04/09 18:20 | 46 | [136] Denis Kudla v Mayer, Leonardo [145] | 6-3,4-6,4-6 | |
| ATP Houston Qual | 04/08 21:20 | 45 | [175] Smyczek, Tim v Mayer, Leonardo [145] | 6-3,4-6,6-7 | |
| Challenger - Buenos Aires | 03/19 16:15 | 29 | [141] Mayer, Leonardo v Taro Daniel [119] | 7-5,3-6,4-6 | |
| Challenger - Buenos Aires | 03/18 14:00 | 28 | [141] Mayer, Leonardo v Tristan Lamasine [205] | 6-1,6-1 |