| Challenger - Kaohsiung | 07/15 07:40 | 25 | Ji Sung Nam v Yuichi Sugita | 4-6,2-6 | |
| ITF - Coreia F1 - Qualificação | 05/02 02:00 | - | Min Hyeok Cho v Ji Sung Nam | 6-4,6-7,6-2 | |
| ITF - Coreia F1 - Qualificação | 05/01 03:00 | - | Cheong-Eui Kim v Ji Sung Nam | 1-6,7-5,2-6 | |
| ITF - Coreia F1 - Qualificação | 04/30 01:00 | - | Ji Sung Nam v Seong Chan Hong | 6-0,6-2 | |
| ITF - Coreia F1 | 04/25 03:00 | - | Hyeon Chung v Ji Sung Nam | 6-0,6-0 | |
| ITF - Coreia F1 | 04/24 01:00 | - | Ji Sung Nam v Jung-Woong Na | 7-5,6-2 | |
| ITF - Coreia F1 | 04/22 01:00 | - | Ji Sung Nam v Hyun-Woo Nam | Retired | |
| ITF - China F3 | 03/19 02:00 | - | Ji Sung Nam v Xin Gao | Retired | |
| ITF - China F2 | 03/13 04:00 | - | Ze Zhang v Ji Sung Nam | 2-6,6-2,6-2 | |
| ITF - China F2 | 03/12 04:40 | - | Bowen Ouyang v Ji Sung Nam | 1-6,6-7 | |
| ITF - China F1 - Masculino | 03/06 02:00 | - | Ji Sung Nam v Yan Bai | 6-3,3-6,4-6 |
Nam Ji-sung (born 15 August 1993) is a South Korean tennis player. He has a career high ATP singles ranking of world No. 236 achieved on 12 August 2019. He also has a career high ATP doubles ranking of No. 102 achieved on 3 February 2020.
Playing for South Korea in Davis Cup, Nam has a W/L record of 3–7.