Gengo Kikuchi defeated Katsuki Nagao 6-2 6-2 in the Japan F8 round of 16 on carpet. The upset overturned the form book — Katsuki Nagao came in leading the head-to-head 1–0. Gengo Kikuchi claimed a first win over Katsuki Nagao in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2013-06-17 | Japan F6 | SF | carpet | Katsuki Nagao | 7-6(2) 6-4 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.