Yong Il Yoon defeated Masayuki Ando 6-2 6-3 in the Japan 1 Masters 4 qualifying round on hard. The upset overturned the form book — Masayuki Ando came in leading the head-to-head 1–0. Yong Il Yoon claimed a first win over Masayuki Ando in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1999-06-07 | Japan 1 Masters 1 | R16 | hard | Masayuki Ando | 7-6 6-3 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.