Tetsuya Chaen defeated Oh Hee Kwon 6-1 5-7 7-6 in the Japan F4 round of 32 on hard. The upset overturned the form book — Oh Hee Kwon came in leading the head-to-head 9–2. Tetsuya Chaen narrowed the head-to-head to 9–3.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2006-06-12 | Japan F6 | QF | clay | Tetsuya Chaen | 6-4 7-6(7) |
| 2006-04-10 | Japan F1 | QF | hard | Oh Hee Kwon | 6-2 7-5 |
| 2006-03-20 | Korea Rep F2 | R32 | hard | Oh Hee Kwon | 7-5 6-3 |
| 2006-03-13 | Korea Rep F1 | R16 | hard | Oh Hee Kwon | 6-4 6-3 |
| 2005-08-15 | Indonesia F3 | F | hard | Oh Hee Kwon | 6-3 6-3 |
| 2005-06-20 | Japan F7 | R16 | clay | Oh Hee Kwon | 6-4 7-5 |
| 2005-05-30 | Japan F5 | R16 | hard | Tetsuya Chaen | 7-5 6-3 |
| 2005-04-11 | Japan F1 | R16 | carpet | Oh Hee Kwon | 7-5 7-5 |
| 2001-03-26 | Japan F3 | R32 | clay | Oh Hee Kwon | 6-4 4-6 6-2 |
| 2000-03-18 | Japan F2 | R16 | carpet | Oh Hee Kwon | 7-5 6-2 |
| 1999-10-18 | Japan F5 | R32 | carpet | Oh Hee Kwon | 1-6 6-2 6-2 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.