Matias Oneille defeated Alejandro Fabbri 6-4 6-4 in the Argentina F1 qualifying round on clay. The upset overturned the form book — Alejandro Fabbri came in leading the head-to-head 1–0. Matias Oneille claimed a first win over Alejandro Fabbri in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2004-01-19 | Guatemala F1 | QF | hard | Alejandro Fabbri | 5-7 6-3 7-5 |