Hiroki Ishii defeated Tetsuya Chaen 2-6 7-6 6-3 in the Japan F3 round of 32 on clay. The upset overturned the form book — Tetsuya Chaen came in leading the head-to-head 1–0. Hiroki Ishii claimed a first win over Tetsuya Chaen in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1998-11-18 | Japan F5 | R16 | hard | Tetsuya Chaen | 6-4 6-4 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.