Yong Il Yoon defeated Seung Hoon Lee 6-3 6-2 in the Korea F1 qualifying round on hard. The upset overturned the form book — Seung Hoon Lee came in leading the head-to-head 1–0. Yong Il Yoon claimed a first win over Seung Hoon Lee in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2004-04-12 | Japan F1 | R16 | carpet | Seung Hoon Lee | 6-1 6-4 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.