 Malaysia: M15 Kuala Lumpur - Doubles - Main |
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| 1/8-finals | Zhao Z./Zheng B. | Koay H. S./Leong M. W. K. | 2:1 (6:3, 2:6, 10:6) | details | 28.11.2023 |
| Malaysia: M15 Ipoh Perak - Doubles - Main |
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| Quarter-finals | Alcantara F. C./Rungkat C. | Koay H. S./Leong M. W. K. | 2:0 (7:62, 6:4) | details | 23.11.2023 |
| 1/8-finals | Abd Hazli I. D./Yong L. | Koay H. S./Leong M. W. K. | 0:0 RET. (5:6) | details | 23.11.2023 |
 World: Davis Cup - Group III - Doubles - Relegation |
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| | Koay H. S./Syed Naguib A. | Al Janahi A./Al Marzouqi A. | CAN. | details | 13.08.2022 |
| World: Davis Cup - Group III - Doubles - Main |
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| Group B | Al-Aswad H./Shelbayh A. | Koay H. S./Syed Naguib A. | 2:1 (1:6, 6:1, 6:3) | details | 12.08.2022 |
| Group A | Pham M. T./Trinh L. G. | Koay H. S./Syed Naguib A. | CAN. | details | 11.08.2022 |
| Group A | Makzoume Y./Sleem R. | Koay H. S./Syed Naguib A. | 1:2 (6:3, 2:6, 1:6) | details | 10.08.2022 |
| Malaysia: M15 Kuala Lumpur - Doubles - Main |
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| Quarter-finals | Koay H. S./Syed Naguib A. | Hazawa S./Takeuchi K. | 1:2 (6:4, 5:7, 5:10) | details | 29.07.2022 |
| 1/8-finals | Cui J./Huang T. | Koay H. S./Syed Naguib A. | 1:2 (3:6, 6:2, 13:15) | details | 27.07.2022 |
| Malaysia: M15 Seremban - Doubles - Main |
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| 1/8-finals | Koay H. S./Syed Naguib A. | Masabayashi T./Sumizawa D. | 0:2 (4:6, 1:6) | details | 19.07.2022 |
| World: Davis Cup - Group III - Doubles - Promotion |
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| | Le Quoc-K./Ly Nam H. | Koay H. S./Syed Naguib A. | CAN. | details | 18.09.2021 |
| World: Davis Cup - Group III - Doubles - Main |
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| | Wong C./Wong Hong K. J. | Koay H. S./Syed Naguib A. | 2:0 (6:3, 6:4) | details | 15.09.2021 |
 Tunisia: M15 Monastir 34 - Doubles - Main |
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| 1/8-finals | Mansouri S./Ouakaa A. | Koay H. S./Syed Naguib A. | 2:1 (7:68, 3:6, 10:6) | details | 07.09.2021 |
| World: Davis Cup - Group III - Doubles - Main |
|---|
| | Ballout J./Fakih N. | Koay H. S./Merzuki M. A. | 0:2 (4:6, 3:6) | details | 19.07.2017 |