Ayumi Oka defeated Mari Tanaka 6-2 6-4 in the Kyoto 10K qualifying round on carpet. The upset overturned the form book — Mari Tanaka came in leading the head-to-head 2–0. Ayumi Oka claimed a first win over Mari Tanaka in three meetings, narrowing the head-to-head to 2–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2007-06-04 | Tokyo 10K | QF | hard | Mari Tanaka | 2-6 6-4 6-2 |
| 2005-08-29 | Saitama 10K | R16 | hard | Mari Tanaka | 7-6(4) 6-3 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.