Oh Hee Kwon defeated Yaoki Ishii 6-1 2-6 7-5 in the Japan F1 semi-final on hard. The upset overturned the form book — Yaoki Ishii came in leading the head-to-head 4–0, but Oh Hee Kwon had been the form player, winning 5 of their last 7 on hard. Oh Hee Kwon claimed a first win over Yaoki Ishii in five meetings, narrowing the head-to-head to 4–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2008-03-31 | Japan F3 | SF | hard | Yaoki Ishii | 6-2 6-2 |
| 2006-08-07 | Indonesia F2 | F | hard | Yaoki Ishii | 6-1 7-6(2) |
| 2005-04-25 | Japan F3 | QF | carpet | Yaoki Ishii | 3-6 6-1 6-3 |
| 1999-10-25 | Japan F6 | R16 | carpet | Yaoki Ishii | 6-2 6-2 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.