Nadia Petrova defeated Klara Koukalova 7-5 6-4 in the Berlin round of 32 on grass. The upset overturned the form book — Klara Koukalova came in leading the head-to-head 2–1. Nadia Petrova narrowed the head-to-head to 2–2.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2011-10-03 | Beijing | R64 | hard | Klara Koukalova | 6-3 6-7(3) 6-1 |
| 2010-09-20 | Seoul | SF | hard | Klara Koukalova | 5-4 RET |
| 2005-08-08 | Los Angeles | R16 | hard | Nadia Petrova | 6-2 6-4 |
Each player's serve crossed against the other's return, converted to expected hold of serve. Recent completed matches, ATP, WTA & Challenger. About
Averages over each player's completed matches in the selected window (200 vs 76). ATP, WTA & Challenger.
Performance in the biggest moments — break points, deciding sets and tiebreaks (0–100, higher is better). About