Bianca Koch defeated Anna Zaja 6-4 6-2 in the Koeln 10K qualifying round on clay. The upset overturned the form book — Anna Zaja came in leading the head-to-head 1–0, but Bianca Koch had been the form player, winning 4 of their last 8 on clay. Bianca Koch claimed a first win over Anna Zaja in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2011-01-24 | Kaarst 10K | R16 | carpet | Anna Zaja | 6-3 6-3 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.