Seiko Okamoto defeated Aiko Nakamura 6-1 6-4 in the Haibara 25K qualifying round on carpet. The upset overturned the form book — Aiko Nakamura came in leading the head-to-head 1–0. Seiko Okamoto claimed a first win over Aiko Nakamura in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2005-05-09 | Fukuoka 50K | QF | grass | Aiko Nakamura | 4-6 7-6(2) 6-2 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.