William Mouw of Chino, California, is playing in his first Wyndham Cup. He qualified into the event for the West Team after a string of impressive finishes. He had top finishes at the PING Heather Farr Classic and the Rolex Tournament of Champions in 2017. Mouw is verbally committed to Pepperdine University and is currently No. 11 in the Rolex AJGA Rankings.
| Rank | Event | R1 | R2 | R3 | R4 | Total |
| T13 | 2018 Western Junior Championship | 71 | 68 | 139 | ||
| 5 | Thunderbird International Junior | 70 | 71 | 68 | 209 | |
| T20 | 2018 Junior Invitational at Sage Valley Golf Club | 76 | 76 | 74 | 226 | |
| 2 | PING Heather Farr Classic | 70 | 65 | 66 | 201 | |
| 4 | Rolex Tournament of Champions | 70 | 69 | 65 | 77 | 281 |
| T19 | The Junior PLAYERS Championship presented by TaylorMade-adidas Golf | 69 | 75 | 74 | 218 | |
| T70 | 2017 Junior PGA Championship - Boys | 74 | 75 | 149 | ||
| 5 | 2017 IMG Academy Junior World Championship | 70 | 71 | 72 | 74 | 287 |