Polona Hercog defeated Andrea Petkovic 6-4 6-3 in the Toronto qualifying round 2 on hard. The upset overturned the form book — Andrea Petkovic came in leading the head-to-head 2–1. Polona Hercog narrowed the head-to-head to 2–2.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2018-03-19 | Miami | R128 | hard | Andrea Petkovic | 6-2 6-0 |
| 2011-05-09 | Rome | R32 | clay | Polona Hercog | 6-4 6-3 |
| 2011-02-05 | Fed Cup WG2 R1: SLO vs GER | RR | clay | Andrea Petkovic | 6-1 6-2 |
Averages from each player's recent completed matches (20 vs 20). ATP, WTA & Challenger.