| 1. Round | 17/03/2018 | Seattle Sounders 2 | - | Portland Timbers 2 | 2:1 |  |
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| 1. Round | 25/03/2018 | Swope Park Rangers | - | Seattle Sounders 2 | 4:2 | ||||
| 2. Round | 12/04/2018 | Seattle Sounders 2 | - | Real Monarchs SLC | 1:3 | ||||
| 5. Round | 02/07/2018 | Los Angeles Galaxy II | - | Seattle Sounders 2 | 5:3 | |
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| 5. Round | 15/07/2018 | Real Monarchs SLC | - | Seattle Sounders 2 | 2:0 | ||||
| 5. Round | 27/07/2018 | Seattle Sounders 2 | - | Las Vegas Lights FC | 3:0 | ||||
| 6. Round | 05/08/2018 | Saint Louis FC | - | Seattle Sounders 2 | 2:0 | |
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| 6. Round | 12/08/2018 | Seattle Sounders 2 | - | San Antonio FC | 3:2 | ||||
| 6. Round | 26/08/2018 | OKC Energy FC | - | Seattle Sounders 2 | 3:0 | |
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| 6. Round | 30/08/2018 | Seattle Sounders 2 | - | Saint Louis FC | 1:1 | ||||
| 7. Round | 09/09/2018 | Sacramento Republic | - | Seattle Sounders 2 | 3:0 |  |
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| 7. Round | 23/09/2018 | Rio Grande Valley FC | - | Seattle Sounders 2 | 3:0 | ||||
| 8. Round | 04/10/2018 | Seattle Sounders 2 | - | Los Angeles Galaxy II | 2:2 | |
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| 8. Round | 11/10/2018 | Seattle Sounders 2 | - | Colorado Springs Switchbacks | 2:2 |
Mexico
USA