Natalia Guitler defeated Estefania Donnet 6-4 3-6 6-1 in the Curitiba 10K round of 16 on clay. The upset overturned the form book — Estefania Donnet came in leading the head-to-head 1–0. Natalia Guitler claimed a first win over Estefania Donnet in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2009-08-10 | Buenos Aires 10K | R32 | clay | Estefania Donnet | 4-6 6-3 6-2 |