Spain: Barcelona - Singles - Main |
| 1/8-finals | Gimeno Valero C. | O'Connell C. | 0:1 RET. (65:7, 2:5) | details | 08.10.2020 |
| 1/16-finals | Bolt A. | O'Connell C. | 0:2 (1:6, 2:6) | details | 06.10.2020 |
Italy: Biella - Singles - Main |
| Semi-finals | Bagnis F. | O'Connell C. | 2:0 (6:4, 6:4) | details | 03.10.2020 |
| Quarter-finals | Istomin D. | O'Connell C. | 0:2 (3:6, 3:6) | details | 03.10.2020 |
| 1/8-finals | Ficovich J. P. | O'Connell C. | 1:2 (7:5, 4:6, 1:6) | details | 01.10.2020 |
| 1/16-finals | Ramanathan R. | O'Connell C. | 0:2 (4:6, 2:6) | details | 29.09.2020 |
France: French Open - Singles - Qualification |
| Quarter-finals | O'Connell C. | Ymer E. | 0:2 (5:7, 4:6) | details | 21.09.2020 |
France: Aix en Provence - Singles - Main |
| 1/16-finals | O'Connell C. | Otte O. | CAN. | details | 08.09.2020 |
USA: US Open - Singles - Main |
| 1/32-finals | O'Connell C. | Medvedev D. | 0:3 (3:6, 2:6, 4:6) | details | 04.09.2020 |
| 1/64-finals | O'Connell C. | Djere L. | 3:1 (4:6, 6:4, 7:62, 6:4) | details | 02.09.2020 |
World: UTR Pro Match Series - Singles - Main |
| | O'Connell C. | Hijikata R. | 0:1 RET. (3:6) | details | 09.07.2020 |
| | O'Connell C. | McCabe J. | 2:0 (6:3, 6:1) | details | 08.07.2020 |
| | O'Connell C. | Hijikata R. | 0:0 RET. (5:2) | details | 30.06.2020 |
| | O'Connell C. | Purcell M. | 0:2 (1:6, 0:6) | details | 29.06.2020 |
World: Others matches - Singles - Main |
| | O'Connell C. | Pearson K. | 2:0 (6:1, 6:4) | details | 28.06.2020 |
| | O'Connell C. | Smith J. | 2:0 (6:2, 6:1) | details | 27.06.2020 |
USA: Indian Wells - Singles - Main |
| 1/16-finals | O'Connell C. | Korda S. | 0:2 (1:6, 1:6) | details | 04.03.2020 |
USA: Columbus - Singles - Main |
| 1/8-finals | O'Connell C. | Rodionov J. | 1:2 (7:64, 65:7, 2:6) | details | 27.02.2020 |
| 1/16-finals | O'Connell C. | Bangoura S. | 2:0 (6:4, 6:2) | details | 26.02.2020 |
Canada: Drummondville - Singles - Main |
| Semi-finals | Rinderknech A. | O'Connell C. | 2:0 (6:4, 6:2) | details | 22.02.2020 |
| Quarter-finals | O'Connell C. | Korda S. | 2:0 (6:3, 6:4) | details | 22.02.2020 |
| 1/8-finals | O'Connell C. | Nam Ji S. | 2:1 (6:1, 4:6, 6:4) | details | 20.02.2020 |
| 1/16-finals | O'Connell C. | Escoffier A. | 2:0 (6:3, 6:4) | details | 19.02.2020 |
USA: Cleveland - Singles - Main |
| 1/16-finals | Aragone J. | O'Connell C. | 2:0 (7:65, 6:2) | details | 11.02.2020 |
USA: Dallas - Singles - Main |
| 1/16-finals | O'Connell C. | Menezes J. | 1:2 (6:3, 4:6, 67:7) | details | 05.02.2020 |
Australia: Australian Open - Singles - Main |
| 1/64-finals | O'Connell C. | Rublev A. | 1:3 (3:6, 6:0, 4:6, 65:7) | details | 21.01.2020 |
Australia: Bendigo - Singles - Main |
| Quarter-finals | O'Connell C. | Travaglia S. | 0:2 (4:6, 2:6) | details | 16.01.2020 |
| 1/8-finals | O'Connell C. | Crnokrak A. | 2:0 (6:4, 6:3) | details | 15.01.2020 |
| 1/16-finals | O'Connell C. | Caruana L. | 2:0 (6:3, 6:1) | details | 14.01.2020 |
New Caledonia: Noumea - Singles - Main |
| 1/8-finals | Klizan M. | O'Connell C. | 2:0 (7:62, 6:2) | details | 09.01.2020 |
| 1/16-finals | Popko D. | O'Connell C. | 0:2 (69:7, 4:6) | details | 08.01.2020 |
USA: Houston - Singles - Main |
| Semi-finals | Karlovic I. | O'Connell C. | 2:1 (65:7, 6:3, 6:4) | details | 16.11.2019 |
| Quarter-finals | O'Connell C. | Mmoh M. | 0:0 RET. (5:0) | details | 16.11.2019 |
| 1/8-finals | O'Connell C. | Menendez-Maceiras A. | 2:0 (7:63, 6:4) | details | 15.11.2019 |
| 1/16-finals | O'Connell C. | Vavassori A. | 2:1 (6:3, 5:7, 6:4) | details | 13.11.2019 |
USA: Knoxville - Singles - Main |
| Final | O'Connell C. | Mmoh M. | 0:2 (4:6, 4:6) | details | 10.11.2019 |
| Semi-finals | Paul T. | O'Connell C. | 0:2 (63:7, 3:6) | details | 09.11.2019 |
| Quarter-finals | Escobedo E. | O'Connell C. | 1:2 (7:62, 4:6, 4:6) | details | 08.11.2019 |
| 1/8-finals | Polansky P. | O'Connell C. | 0:2 (2:6, 3:6) | details | 07.11.2019 |
| 1/16-finals | King K. | O'Connell C. | 0:2 (5:7, 3:6) | details | 05.11.2019 |
USA: Charlottesville - Singles - Main |
| 1/8-finals | O'Connell C. | Pospisil V. | 0:2 (3:6, 2:6) | details | 01.11.2019 |
| 1/16-finals | O'Connell C. | Bellucci T. | 2:0 (6:3, 6:4) | details | 29.10.2019 |
USA: Las Vegas - Singles - Main |
| Semi-finals | O'Connell C. | Pospisil V. | 0:2 (4:6, 3:6) | details | 19.10.2019 |
| Quarter-finals | O'Connell C. | Giron M. | 2:1 (7:67, 3:6, 7:66) | details | 18.10.2019 |
| 1/8-finals | Peniston R. | O'Connell C. | 1:2 (3:6, 7:5, 2:6) | details | 17.10.2019 |
| 1/16-finals | Mejia N. | O'Connell C. | 0:2 (3:6, 2:6) | details | 16.10.2019 |
USA: Fairfield - Singles - Main |
| Final | Johnson S. | O'Connell C. | 0:2 (4:6, 4:6) | details | 13.10.2019 |
| Semi-finals | O'Connell C. | King K. | 2:0 (6:3, 7:62) | details | 12.10.2019 |
| Quarter-finals | O'Connell C. | Draper J. | 2:0 (6:2, 6:3) | details | 11.10.2019 |