| ATP Auckland | 01/05 03:00 | 64 | Mackenzie McDonald v Duckhee Lee | Cancelled | |
| Challenger Noumea | 01/01 01:25 | 25 | [218] Duckhee Lee v Hugo Nys [79] | 6-4,4-6,2-6 | |
| Australian Open - Wild card | 12/01 05:50 | 28 | [203] Duckhee Lee v Zhe Li [256] | 6-7,3-6 | |
| Australian Open - Wild card | 11/30 06:30 | 27 | Duckhee Lee v Renta Tokuda | 6-4,6-4 | |
| Australian Open - Wild card | 11/29 04:40 | 26 | Duckhee Lee v Hanyi Liu | 6-1,6-2 | |
| Challenger Kobe | 11/12 05:00 | 25 | Duckhee Lee v Ji Sung Nam | Cancelled | |
| Challenger Shenzhen 2 | 10/29 04:20 | 25 | [226] Federico Gaio v Duckhee Lee [197] | Retired | |
| Challenger Liuzhou | 10/24 06:00 | 26 | [89] Radu Albot v Duckhee Lee [197] | 6-2,7-5 | |
| Challenger Liuzhou | 10/22 04:15 | 25 | [197] Duckhee Lee v Tsung-Hua Yang [270] | 6-2,6-3 | |
| Challenger Tashkent | 10/08 14:10 | 25 | [233] Evgeny Karlovskiy v Duckhee Lee [205] | 7-6,6-4 | |
| Challenger Kaohsiung | 09/22 08:10 | 28 | [42] Gael Monfils v Duckhee Lee [232] | 6-1,6-1 | |
| Challenger Kaohsiung | 09/21 12:05 | 27 | [232] Duckhee Lee v Frederico Ferreira Silva [310] | 6-2,7-5 | |
| Challenger Kaohsiung | 09/20 10:00 | 26 | [123] Jason Jung v Duckhee Lee [232] | 6-7,4-6 | |
| Challenger Kaohsiung | 09/19 08:50 | 25 | [267] Tomislav Brkic v Duckhee Lee [232] | 2-6,6-7 | |
| Davis Cup | 09/15 03:35 | 29 | [231] Duckhee Lee v Rubin Statham [207] | 6-4,6-1 | |
| Davis Cup | 09/14 04:05 | 29 | [231] Duck Hee Lee v Michael Venus [15] | 7-5,6-7,6-2 | |
| Challenger Zhangjiagang | 09/06 04:20 | 26 | [204] Uladzimir Ignatik v Duckhee Lee [229] | 7-6,6-1 | |
| Challenger Zhangjiagang | 09/04 07:30 | 25 | [229] Duckhee Lee v Ze Zhang [168] | 6-3,5-7,6-0 | |
| Challenger Gwangju | 08/17 02:00 | 27 | [241] Duckhee Lee v Makoto Ochi [438] | 2-6,1-6 | |
| Challenger Gwangju | 08/15 06:00 | 26 | [241] Duckhee Lee v Rubin Statham [232] | 6-4,6-3 | |
| Challenger Gwangju | 08/14 06:30 | 25 | Duckhee Lee v Hong Chung | 7-6,6-2 | |
| Challenger Jinan | 08/10 07:30 | 27 | [305] James Ward v Duck Hee Lee [239] | 3-6,7-5,6-4 | |
| Challenger Jinan | 08/08 12:40 | 26 | [239] Duck Hee Lee v Yibing Wu [329] | 6-0,6-3 | |
| Challenger Jinan | 08/07 02:00 | 25 | Manish Sureshkumar v Duck Hee Lee | 1-6,3-6 | |
| Challenger Chengdu | 08/02 08:05 | 26 | [240] Duckhee Lee v James Ward [329] | 6-4,5-7,3-6 | |
| Challenger Chengdu | 07/31 06:05 | 25 | [161] Nikola Milojevic v Duckhee Lee [240] | 4-6,4-6 | |
| Challenger Astana | 07/19 07:50 | 26 | [228] Duckhee Lee v Pavel Kotov [445] | 7-5,6-7,5-7 | |
| Challenger Astana | 07/17 11:10 | 25 | Duckhee Lee v Sagadat Ayap | 6-4,6-2 | |
| Wimbledon Qual | 06/25 16:35 | 44 | Attila Balazs v Duckhee Lee | 6-3,5-7,6-1 | |
| ATP Antalya Qual | 06/23 11:00 | 64 | [302] Filip Horansky v Duckhee Lee [233] | 7-5,6-2 |