Federico Dondo defeated Matias Oneille 6-2 6-1 in the Uruguay F3 round of 32 on clay. The upset overturned the form book — Matias Oneille came in leading the head-to-head 1–0. Federico Dondo claimed a first win over Matias Oneille in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1999-07-19 | Uruguay F1 | R16 | clay | Matias Oneille | 6-0 7-6 |