Oscar Bustos defeated William Kyriakos 7-6 6-1 in the Brazil 2 Masters 3 round of 32 on clay. The upset overturned the form book — William Kyriakos came in leading the head-to-head 1–0. Oscar Bustos claimed a first win over William Kyriakos in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1991-03-18 | Brazil 1 Masters 1 | R16 | clay | William Kyriakos | 6-2 6-3 |