Arata Onozawa defeated Tasuku Iwami 7-6 7-6 in the Japan F9 round of 32 on hard. The upset overturned the form book — Tasuku Iwami came in leading the head-to-head 3–1. Arata Onozawa narrowed the head-to-head to 3–2.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2010-05-31 | Guam F1 | QF | hard | Tasuku Iwami | 7-6(8) 6-2 |
| 2009-06-08 | Japan F4 | R32 | clay | Arata Onozawa | 2-6 6-3 6-4 |
| 2009-03-16 | Japan F1 | R16 | hard | Tasuku Iwami | 6-3 3-6 6-1 |
| 2008-03-17 | Japan F1 | QF | hard | Tasuku Iwami | 6-2 6-1 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.