Martin Vassallo Arguello defeated Federico Dondo 6-4 7-5 in the Argentina F5 round of 32 on clay. The upset overturned the form book — Federico Dondo came in leading the head-to-head 3–0. Martin Vassallo Arguello claimed a first win over Federico Dondo in four meetings, narrowing the head-to-head to 3–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1999-05-17 | Chile F2 | R32 | clay | Federico Dondo | 7-6 6-3 |
| 1999-05-10 | Chile F1 | R16 | clay | Federico Dondo | 6-3 3-6 6-4 |
| 1998-11-16 | Brazil F5 | R16 | clay | Federico Dondo | 2-6 6-3 7-6 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.