Seiko Okamoto defeated Remi Tezuka 6-3 6-4 in the Incheon 25K round of 32 on hard. The upset overturned the form book — Remi Tezuka came in leading the head-to-head 2–1. Seiko Okamoto narrowed the head-to-head to 2–2.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2010-03-22 | Kofu 10K | R32 | hard | Remi Tezuka | 6-3 6-4 |
| 2000-06-26 | Lachine 10K | R16 | clay | Remi Tezuka | 6-4 6-3 |
| 1999-09-06 | Ibaraki 2 10K | QF | hard | Seiko Okamoto | 6-4 6-4 |