Rafael Serpa Guinazu defeated Matias Oneille 6-4 6-4 in the Argentina 2 qualifying round on clay. The upset overturned the form book — Matias Oneille came in leading the head-to-head 3–1. Rafael Serpa Guinazu narrowed the head-to-head to 3–2.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2000-07-31 | Argentina F8 | SF | clay | Rafael Serpa Guinazu | 6-4 3-6 6-4 |
| 2000-06-12 | Argentina 1 | R16 | clay | Matias Oneille | 6-4 7-6(3) |
| 1999-07-31 | Argentina 2 Masters 4 | R16 | clay | Matias Oneille | 1-6 7-6 7-6 |
| 1999-05-29 | Argentina 1 Masters 2 | R32 | clay | Matias Oneille | 6-3 6-0 |