Estefania Donnet defeated Natalia Guitler 4-6 6-3 6-2 in the Buenos Aires 10K round of 32 on clay. The upset overturned the form book — Natalia Guitler came in leading the head-to-head 1–0, but Estefania Donnet had been the form player, winning 4 of their last 7 on clay. Estefania Donnet claimed a first win over Natalia Guitler in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2008-09-29 | Curitiba 10K | R16 | clay | Natalia Guitler | 6-4 3-6 6-1 |