Stadium: Court 2 Round: 54 Ground: Clay
| ITF M15 Esch/Alzette | 2021/07/21 14:25 | Guillaume Dermiens v Patrick Kypson | 1-6,3-6 |
| ITF M15 Esch/Alzette | 2021/07/20 12:55 | Guillaume Dermiens v Raphael Calzi | 1-6,6-4,6-4 |
| ITF M15 Esch/Alzette | 2021/07/19 09:00 | Lucas Szewczyk v Guillaume Dermiens | 3-6,2-6 |
| ITF M15 Esch/Alzette | 2021/07/18 14:25 | Floris Podzimek v Guillaume Dermiens | 3-6,1-6 |
| ITF M25 Marburg | 2021/07/05 08:00 | Florian Broska v Guillaume Dermiens | 7-5,6-4 |
| ITF M25 Alkmaar | 2021/06/21 14:25 | Guillaume Dermiens v Zachary Eisinga | 4-6,7-5,13-11 |
| ITF M25 Alkmaar | 2021/06/20 10:30 | Takanyi Garanganga v Guillaume Dermiens | 3-6,1-6 |
| ITF M15 Antalya | 2021/06/08 07:00 | Franco Roncadelli v Guillaume Dermiens | 6-2,6-0 |
| ITF M25 Koksijde | 2021/08/15 12:30 | Max Van Wijk v Alen Moritz Hodzic | 1-6,3-6 |
| ITF M25 Kiseljak | 2021/05/23 13:15 | Valentin Lapalu v Alen Moritz Hodzic | 6-4,6-2 |
| ITF M15 Sibenik | 2021/05/16 15:00 | Alen Moritz Hodzic v Peter Goldsteiner | 6-3,5-7,5-10 |