Sophie Guo of (Chine) Orlando, Florida, will be making her Wyndham Cup debut at Old Sandwich Golf Club. The junior earned her spot by finishing T4 at the 2017 Polo Golf Junior Classic and winning the 2018 Callaway Golf / Ollie Schniederjans Junior Classic. Guo is currently No. 15 in the Rolex AJGA Rankings.
| Rank | Event | R1 | R2 | R3 | R4 | Total |
| T15 | Thunderbird International Junior | 74 | 70 | 76 | 220 | |
| 1 | Callaway Golf / Ollie Schniederjans Junior Classic | 69 | 70 | 74 | 213 | |
| T23 | Rolex Tournament of Champions | 75 | 72 | 75 | 76 | 298 |
| T7 | The PING Invitational | 73 | 75 | 72 | 220 | |
| QWD0 | Swinging Skirts AJGA Invitational | 82 | 78 | 0 | ||
| 9 | 2017 Junior PGA Championship - Girls | 68 | 68 | 72 | 72 | 280 |
| T4 | Polo Golf Junior Classic | 70 | 77 | 71 | 72 | 290 |