Oscar Martinez Dieguez defeated Juan Carlos Ferrero 7-6 7-6 in the Spain 4 Masters 2 round of 32 on clay. The upset overturned the form book — Juan Carlos Ferrero came in leading the head-to-head 2–0. Oscar Martinez Dieguez claimed a first win over Juan Carlos Ferrero in three meetings, narrowing the head-to-head to 2–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1998-07-20 | Spain F3 | QF | clay | Juan Carlos Ferrero | 6-1 6-2 |
| 1998-01-30 | Spain 2 Masters 3 | R32 | clay | Juan Carlos Ferrero | 6-4 6-1 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.