Florencia Labat defeated Kathy Rinaldi Stunkel 6-2 6-2 in the US Open round of 128 on hard. The upset overturned the form book — Kathy Rinaldi Stunkel came in leading the head-to-head 1–0, defending last year's round of 128. Florencia Labat claimed a first win over Kathy Rinaldi Stunkel in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1990-08-27 | US Open | R128 | hard | Kathy Rinaldi Stunkel | 6-4 4-6 6-3 |