Carlos Zwetsch defeated Mathias Huning 6-2 7-6 in the Brazil 2 Masters 3 round of 16 on clay. The upset overturned the form book — Mathias Huning came in leading the head-to-head 1–0, but Carlos Zwetsch had been the form player, winning 2 of their last 5 on clay. Carlos Zwetsch claimed a first win over Mathias Huning in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1991-03-18 | Brazil 1 Masters 1 | R32 | clay | Mathias Huning | 6-1 7-5 |