Adriano Ferreira defeated Joao Zwetsch 6-3 6-2 in the Argentina F1 round of 32 on clay. The upset overturned the form book — Joao Zwetsch came in leading the head-to-head 1–0. Adriano Ferreira claimed a first win over Joao Zwetsch in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1991-05-13 | Brazil 3 Masters 2 | R32 | clay | Joao Zwetsch | 6-3 3-6 6-2 |