Stadium: Court 3 Round: 14 Ground: Clay
| Challenger Buenos Aires | 2021/10/18 16:30 | Martin Cuevas v Guido Ivan Justo | 6-3,6-3 |
| Challenger Buenos Aires | 2021/10/17 17:15 | Guido Ivan Justo v Federico Zeballos | 6-2,6-1 |
| ITF M15 Monastir | 2021/05/18 08:30 | Thomas Fancutt v Guido Ivan Justo | 6-2,6-4 |
| ITF M15 Monastir | 2021/05/10 08:00 | Guido Ivan Justo v Francois Musitelli | 6-3,4-6,5-10 |
| ITF M15 Monastir | 2021/05/05 08:25 | Guido Ivan Justo v Takashi Saito | 1-6,1-6 |
| ITF M15 Monastir | 2021/04/28 08:30 | Yuta Kawahashi v Guido Ivan Justo | 6-4,6-2 |
| ITF M15 Cordoba | 2021/04/06 14:05 | Tomas Farjat v Guido Ivan Justo | 6-2,6-4 |
| ATP Acapulco | 2021/03/14 04:35 | Guido Ivan Justo v Agustin Velotti | 0-6,1-6 |