Karen Castiblanco defeated Cecilia Costa Melgar 6-4 2-6 6-3 in the Asuncion 10K qualifying round on clay. The upset overturned the form book — Cecilia Costa Melgar came in leading the head-to-head 2–0, but Karen Castiblanco had been the form player, winning 2 of their last 6 on clay. Karen Castiblanco claimed a first win over Cecilia Costa Melgar in three meetings, narrowing the head-to-head to 2–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2011-10-24 | Bogota 10K | SF | clay | Cecilia Costa Melgar | 7-5 6-2 |
| 2008-11-10 | Santiago 10K | QF | clay | Cecilia Costa Melgar | 4-6 6-3 6-2 |