Naoko Sawamatsu defeated Conchita Martinez 7-6 6-4 in the Tokyo quarter-final on hard. The upset overturned the form book — Conchita Martinez came in leading the head-to-head 1–0. Naoko Sawamatsu claimed a first win over Conchita Martinez in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1998-03-19 | Key Biscayne | R32 | hard | Conchita Martinez | 6-2 6-2 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.