Yosuke Watanuki defeated Masaki Sasai 5-7 6-3 6-1 in the Japan F4 round of 32 on hard. The upset overturned the form book — Masaki Sasai came in leading the head-to-head 1–0, but Yosuke Watanuki had been the form player, winning 3 of their last 7 on hard. Yosuke Watanuki claimed a first win over Masaki Sasai in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2015-06-08 | Japan F6 | R16 | hard | Masaki Sasai | 6-3 6-2 |
Averages over each player's completed matches in the selected window (198 vs 1). 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. Small sample — read as indicative. About