Yumi Nakano defeated Ayumi Oka 6-7 6-3 6-4 in the Nishi Tama 10K round of 32 on hard. The upset overturned the form book — Ayumi Oka came in leading the head-to-head 2–0. Yumi Nakano claimed a first win over Ayumi Oka in three meetings, narrowing the head-to-head to 2–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2010-03-22 | Kofu 10K | R32 | hard | Ayumi Oka | 6-4 6-4 |
| 2008-06-09 | Tokyo 10K | R32 | hard | Ayumi Oka | 6-1 6-3 |