| Challenger - Guangzhou | 09/08 08:35 | 14 | Colin Sinclair v Zhenxiong Dong | 0-1 | |
| ITF - M15 Hong Kong | 09/08 02:00 | 29 | Colin Sinclair v Chris Rodesch | 4-6,6-7 | |
| ITF - M15 Hong Kong | 09/07 06:45 | 28 | Colin Sinclair v Samir Banerjee | 6-2,7-5 | |
| ITF - M15 Hong Kong | 09/06 10:40 | 27 | [331] Colin Sinclair v Edward Winter [315] | 6-7,6-3,10-5 | |
| ITF - M15 Hong Kong | 09/05 04:25 | 26 | Colin Sinclair v Yan Cheng Chen | 6-4,6-3 | |
| ITF - M15 Hong Kong | 09/03 07:00 | 25 | Colin Sinclair v Jimmy Yang | 6-1,6-4 | |
| ITF - M25 Hong Kong | 08/29 01:55 | 26 | [352] Woobin Shin v Colin Sinclair [331] | 7-6,7-6 | |
| ITF - M25 Hong Kong | 08/28 03:35 | 25 | Ren Nakamura v Colin Sinclair | 6-7,4-6 | |
| ITF - M15 Huntsville | 08/15 15:00 | 27 | Colin Sinclair v Leo Vithoontien | 6-7,6-4,5-7 | |
| ITF - M15 Huntsville | 08/14 14:00 | 26 | Colin Sinclair v Ilyas Milad Fahim | 6-4,6-1 | |
| ITF - M15 Huntsville | 08/13 19:55 | 25 | Colin Sinclair v Kian Vakili | 6-4,7-6 | |
| ITF - M25 Southaven | 08/08 21:55 | 26 | Leo Vithoontien v Colin Sinclair | 6-7,6-3,7-6 |
Colin Sinclair (born December 19, 1994) is an American tennis player representing the Northern Mariana Islands.
He achieved a career best singles ranking of world No. 340 on 18 September 2023, and a career high doubles ranking of world No. 200 on 10 April 2023. He has won 2 singles titles on the ITF Futures Tour. Additionally, he has won 2 titles on ATP Challenger Tour and 7 titles on the ITF Futures Tour in doubles.
He represents the Northern Mariana Islands in Davis Cup as part of the Pacific Oceania team since 2017 and has a career record of 18–5 (13–3 in singles, 5–2 in doubles) in the competition. He has been coached by Jeff Race, Ian Malpass, and Silviu Tanasoiu.