Ji Hoon Son defeated Seong Gook Oh 6-3 6-3 in the Seoul CH qualifying round 1 on hard. The upset overturned the form book — Seong Gook Oh came in leading the head-to-head 1–0, but Ji Hoon Son had been the form player, winning 3 of their last 4 on hard. Ji Hoon Son claimed a first win over Seong Gook Oh in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2017-06-26 | Korea F5 | R32 | clay | Seong Gook Oh | 7-5 6-1 |
Averages over each player's completed matches in the selected window (72 vs 19). 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