Natalia Garbellotto defeated Valentina Castro 2-6 6-2 6-3 in the Asuncion 10K round of 16 on clay. The upset overturned the form book — Valentina Castro came in leading the head-to-head 1–0, but Natalia Garbellotto had been the form player, winning 3 of their last 4 on clay. Natalia Garbellotto claimed a first win over Valentina Castro in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2005-05-09 | Los Mochis 10K | QF | clay | Valentina Castro | 6-4 4-6 6-4 |