Valentina Castro defeated Natalia Garbellotto 6-4 4-6 6-4 in the Los Mochis 10K qualifying round on clay. The upset overturned the form book — Natalia Garbellotto came in leading the head-to-head 1–0. Valentina Castro claimed a first win over Natalia Garbellotto in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2003-09-01 | Asuncion 10K | R16 | clay | Natalia Garbellotto | 2-6 6-2 6-3 |