| 1. Round | 29/03/2018 | Seattle Sounders 2 | - | Fresno FC | 0:1 |  |
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| 2. Round | 08/04/2018 | Sacramento Republic | - | Seattle Sounders 2 | 1:0 | ||||
| 2. Round | 15/04/2018 | Seattle Sounders 2 | - | Rio Grande Valley FC | 3:2 | ||||
| 2. Round | 22/04/2018 | Colorado Springs Switchbacks | - | Seattle Sounders 2 | 0:0 |  |
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| 3. Round | 13/05/2018 | Seattle Sounders 2 | - | Portland Timbers 2 | 0:1 | ||||
| 3. Round | 20/05/2018 | Reno 1868 FC | - | Seattle Sounders 2 | 1:1 | ||||
| 4. Round | 03/06/2018 | Fresno FC | - | Seattle Sounders 2 | 4:0 | ||||
| 4. Round | 10/06/2018 | Seattle Sounders 2 | - | OKC Energy FC | 2:1 | ||||
| 4. Round | 17/06/2018 | Las Vegas Lights FC | - | Seattle Sounders 2 | 4:1 |  |
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| 5. Round | 02/07/2018 | Los Angeles Galaxy II | - | Seattle Sounders 2 | 5:3 | |
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| 5. Round | 06/07/2018 | Seattle Sounders 2 | - | Swope Park Rangers | 0:2 | |
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| 5. Round | 08/07/2018 | Seattle Sounders 2 | - | Reno 1868 FC | 1:2 |
USA