Germany: M15 Kamen - Singles - Main |
| 1/16-finals | Willems J. | Moraing O. | 0:2 (64:7, 5:7) | details | 22.06.2022 |
Germany: International Premier League B - Singles - Main |
| | Simon T. | Willems J. | CAN. | details | 28.07.2020 |
| | Valsecchi P. | Willems J. | 2:1 (1:6, 7:5, 6:2) | details | 27.07.2020 |
Germany: Hamburg - Singles - Main |
| 1/16-finals | Seifert S. | Willems J. | 2:1 (4:6, 6:3, 6:2) | details | 23.10.2018 |
Germany: Saarlouis - Singles - Main |
| 1/16-finals | Willems J. | Davydenko P. | RET. (0:4) | details | 03.07.2018 |
Germany: Kamen - Singles - Main |
| 1/8-finals | Eriksson M. | Willems J. | 2:0 (6:3, 6:0) | details | 28.06.2018 |
| 1/16-finals | Diarra G. | Willems J. | 0:2 (1:6, 2:6) | details | 26.06.2018 |
Germany: Saarlouis - Singles - Main |
| 1/16-finals | Pereira J. | Willems J. | 2:1 (4:6, 6:3, 6:2) | details | 04.07.2017 |
Germany: Kamen - Singles - Main |
| Quarter-finals | Hoang A. | Willems J. | 2:0 (6:3, 6:2) | details | 30.06.2017 |
| 1/8-finals | Martinez Sarrasague F. | Willems J. | 0:2 (66:7, 64:7) | details | 29.06.2017 |
| 1/16-finals | Willems J. | Mylokostov D. | 2:1 (2:6, 7:5, 6:1) | details | 28.06.2017 |
Spain: Cornella - Singles - Main |
| 1/16-finals | Willems J. | Roca Batalla O. | 0:2 (3:6, 1:6) | details | 20.02.2017 |
Germany: Kaarst - Singles - Main |
| 1/16-finals | Mannapov A. | Willems J. | 2:0 (6:4, 6:4) | details | 18.01.2017 |
Germany: Karlsruher - Singles - Main |
| 1/8-finals | Boehler D. | Willems J. | 2:0 (6:2, 7:5) | details | 18.08.2016 |
| 1/16-finals | Willems J. | Kern R. | 2:0 (6:4, 6:4) | details | 17.08.2016 |
Germany: Essen - Singles - Main |
| Quarter-finals | Willems J. | Nakagawa N. | 1:2 (7:5, 5:7, 65:7) | details | 04.08.2016 |
| 1/8-finals | Banes M. | Willems J. | 0:2 (1:6, 3:6) | details | 04.08.2016 |
| 1/16-finals | Gawron M. | Willems J. | 0:2 (3:6, 5:7) | details | 02.08.2016 |
Germany: Saarlouis - Singles - Main |
| Semi-finals | Willems J. | Netuschil M. | 0:2 (3:6, 3:6) | details | 09.07.2016 |
| Quarter-finals | Willems J. | Razborsek N. | 2:0 (6:3, 7:66) | details | 08.07.2016 |
| 1/8-finals | Sieber M. | Willems J. | 0:2 (4:6, 3:6) | details | 07.07.2016 |
| 1/16-finals | Willems J. | Venturino T. | 2:0 (6:3, 6:3) | details | 06.07.2016 |
Germany: Kamen - Singles - Main |
| 1/16-finals | Jebens H. | Willems J. | 2:1 (5:7, 7:5, 6:1) | details | 29.06.2016 |
Germany: Kaarst - Singles - Main |
| 1/16-finals | Willems J. | Altmaier D. | 0:2 (3:6, 3:6) | details | 20.01.2015 |
Germany: Essen - Singles - Main |
| 1/16-finals | Willems J. | Arends S. | 1:2 (6:1, 4:6, 1:6) | details | 15.10.2013 |
Germany: Kaarst - Singles - Main |
| 1/16-finals | Willems J. | Pepe F. | 0:2 (2:6, 2:6) | details | 23.01.2013 |