Geraldine Aizenberg defeated Natalia Gussoni 6-3 7-5 in the Asuncion 10K round of 32 on clay. The upset overturned the form book — Natalia Gussoni came in leading the head-to-head 1–0, but Geraldine Aizenberg had been the form player, winning 7 of their last 9 on clay. Geraldine Aizenberg claimed a first win over Natalia Gussoni in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1999-03-29 | Santiago 10K | R16 | clay | Natalia Gussoni | 6-1 7-5 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.