| ATP Pekin | 10/02 04:30 | 25 | [58] Matteo Berrettini v Leonardo Mayer [52] | 6-3,6-2 | |
| US Open | 08/28 15:00 | 23 | [89] Laslo Djere v Leonardo Mayer [43] | Retired | |
| ATP Winston-Salem | 08/21 23:10 | 25 | [41] Leonardo Mayer v Kyle Edmund [16] | 3-6,3-6 | |
| ATP Winston-Salem | 08/20 19:00 | 24 | [41] Leonardo Mayer v Yuichi Sugita [93] | 6-3,7-6 | |
| ATP Cincinnati | 08/17 18:00 | 26 | [50] Leonardo Mayer v Roger Federer [2] | 1-6,6-7 | |
| ATP Cincinnati | 08/14 18:35 | 25 | [17] Lucas Pouille v Leonardo Mayer [50] | 6-7,4-6 | |
| ATP Cincinnati | 08/13 18:30 | 24 | [133] Michael Mmoh v Leonardo Mayer [50] | 4-6,6-1,4-6 | |
| ATP Hamburg | 07/29 13:00 | 29 | [81] Nikoloz Basilashvili v Leonardo Mayer [36] | 6-4,0-6,7-5 | |
| ATP Hamburg | 07/28 10:00 | 28 | [113] Jozef Kovalik v Leonardo Mayer [36] | 7-6,4-6,6-7 | |
| ATP Hamburg | 07/27 11:30 | 27 | [36] Leonardo Mayer v Diego Schwartzman [12] | 6-3,4-6,6-3 | |
| ATP Hamburg | 07/25 15:30 | 26 | [37] Gael Monfils v Leonardo Mayer [36] | 1-6,5-7 | |
| ATP Hamburg | 07/23 09:00 | 25 | [36] Leonardo Mayer v Albert Ramos-Vinolas [40] | 6-3,6-2 | |
| ATP Bastad | 07/16 11:25 | 25 | [75] Matteo Berrettini v Leonardo Mayer [36] | 3-6,6-3,6-4 | |
| Wimbledon | 07/02 10:30 | 23 | [64] Jan-Lennard Struff v Leonardo Mayer [36] | 3-6,6-7,7-6,7-6,6-1 | |
| ATP Eastbourne | 06/27 14:35 | 26 | [62] John Millman v Leonardo Mayer [36] | 7-6,7-6 | |
| ATP Eastbourne | 06/26 10:00 | 25 | [53] Gilles Simon v Leonardo Mayer [36] | 4-6,6-7 | |
| ATP Queens | 06/20 11:00 | 26 | [62] Frances Tiafoe v Leonardo Mayer [38] | 6-4,2-6,6-4 | |
| ATP Queens | 06/19 11:30 | 25 | [38] Leonardo Mayer v Kevin Anderson [8] | 7-6,4-6,7-6 | |
| French Open | 05/29 17:25 | 23 | [42] Leonardo Mayer v Julien Benneteau [62] | 6-2,6-7,2-6,3-6 | |
| ATP Rzym | 05/14 10:55 | 24 | [42] Leonardo Mayer v David Goffin [10] | 1-6,2-6 | |
| ATP Madryt | 05/10 16:10 | 26 | [45] Leonardo Mayer v Alexander Zverev [3] | 4-6,2-6 | |
| ATP Madryt | 05/09 15:30 | 25 | [45] Leonardo Mayer v Fernando Verdasco [37] | 6-2,6-1 | |
| ATP Madryt | 05/08 10:00 | 24 | [19] Fabio Fognini v Leonardo Mayer [45] | 3-6,4-6 | |
| ATP Estoril | 05/01 16:15 | 25 | [45] Leonardo Mayer v Nicolas Jarry [65] | 6-3,6-7,4-6 | |
| ATP Barcelona | 04/25 16:05 | 25 | [45] Leonardo Mayer v Karen Khachanov [37] | 4-6,3-6 | |
| ATP Barcelona | 04/23 16:20 | 24 | [45] Leonardo Mayer v Mischa Zverev [52] | 6-3,6-0 | |
| ATP Miami | 03/24 15:00 | 24 | [36] Borna Coric v Leonardo Mayer [45] | 6-7,6-3,6-4 | |
| ATP Miami | 03/22 16:25 | 23 | [45] Leonardo Mayer v Donald Young [110] | 3-6,6-4,6-2 | |
| ATP Indian Wells | 03/15 00:50 | 26 | Juan Martin Del Potro v Leonardo Mayer | 3-6,7-6,6-3 | |
| ATP Indian Wells | 03/13 19:40 | 25 | Leonardo Mayer v Taro Daniel | 6-4,6-1 |