Masato Hatanaka defeated Oh Hee Kwon 6-2 6-4 in the Japan F4 round of 32 on clay. The upset overturned the form book — Oh Hee Kwon came in leading the head-to-head 3–0. Masato Hatanaka claimed a first win over Oh Hee Kwon in four meetings, narrowing the head-to-head to 3–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2008-03-24 | Japan F2 | R16 | hard | Oh Hee Kwon | 6-3 6-4 |
| 2007-09-17 | Japan F9 | F | carpet | Oh Hee Kwon | 6-1 6-0 |
| 2000-09-11 | Japan F6 | R32 | hard | Oh Hee Kwon | 6-1 6-1 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.