Seiko Okamoto defeated Su Wei Hsieh 6-3 6-3 in the Hamanako 25K qualifying round on carpet. The upset overturned the form book — Su Wei Hsieh came in leading the head-to-head 3–1. Seiko Okamoto narrowed the head-to-head to 3–2.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2008-10-13 | Makinohara 25K | R16 | carpet | Su Wei Hsieh | 6-2 3-6 6-4 |
| 2005-05-30 | Gunma 25K | F | carpet | Su Wei Hsieh | 6-1 6-2 |
| 2005-02-21 | Taipei 25K | QF | hard | Seiko Okamoto | 7-5 1-6 6-2 |
| 2002-04-15 | Gunma 10K | QF | carpet | Su Wei Hsieh | 6-3 6-3 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.