Ayumi Oka defeated Hiroko Kuwata 6-4 6-0 in the Gifu 50K qualifying round on hard. The upset overturned the form book — Hiroko Kuwata came in leading the head-to-head 2–0, but Ayumi Oka had been the form player, winning 4 of their last 7 on hard. Ayumi Oka claimed a first win over Hiroko Kuwata in three meetings, narrowing the head-to-head to 2–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2012-03-19 | Kofu 10K | QF | hard | Hiroko Kuwata | 4-6 7-5 6-3 |
| 2010-09-20 | Makinohara 25K | QF | carpet | Hiroko Kuwata | 6-4 6-4 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.