Valentin Guenther defeated Pablo Vivero Gonzalez 7-6 7-5 in the M15 Heraklion 4 round of 32 on hard. The upset overturned the form book — Pablo Vivero Gonzalez came in leading the head-to-head 1–0, but Valentin Guenther had been the form player, winning 2 of their last 4 on hard. Valentin Guenther claimed a first win over Pablo Vivero Gonzalez in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2018-04-16 | Egypt F14 | R16 | hard | Pablo Vivero Gonzalez | 6-2 7-6(8) |