Andrea Petkovic defeated Polona Hercog 6-1 6-2 in the SLO vs GER round robin on clay. The upset overturned the form book — Polona Hercog came in leading the head-to-head 1–0. Andrea Petkovic claimed a first win over Polona Hercog in two meetings, levelling the head-to-head at 1–1.
Petkovic A. took it in straight sets.
Petkovic A. and Hercog P. faced 10 of the same opponents in the last 12 months. Petkovic A. went 8–6 (57%) against them, Hercog P. 4–9 (31%). Petkovic A. came out better against 4 of 9 comparable opponents, Hercog P. against 2 — though 1 of those edges carries caveats (retirement).
Andrea Petkovic beat Polona Hercog 6-1 6-2. Umpiry, "Andrea Petkovic vs Polona Hercog — SLO vs GER Round Robin", https://umpiry.com/match/2011-02-05/hercog-vs-petkovic-slo-vs-ger-rr?utm_source=cite (as of 5 February 2011).