Masato Shiga defeated Issei Okamura 6-3 6-1 in the Kobe CH qualifying round 1 on hard. The upset overturned the form book — Issei Okamura came in leading the head-to-head 2–1. Masato Shiga narrowed the head-to-head to 2–2.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2017-06-05 | Japan F7 | R32 | hard | Issei Okamura | 6-4 |
| 2015-08-17 | Chinese Taipei F1 | R16 | hard | Issei Okamura | 6-4 6-4 |
| 2014-03-31 | Japan F4 | QF | hard | Masato Shiga | 6-0 6-3 |
Averages over each player's completed matches in the selected window (54 vs 200). ATP, WTA & Challenger.
Each player's serve crossed against the other's return, converted to expected hold of serve. Recent completed matches, ATP, WTA & Challenger. About