Tanja Ostertag defeated Elizabeth Kaufman 6-4 6-1 in the Mexico City 10K round of 32 on hard. The upset overturned the form book — Elizabeth Kaufman came in leading the head-to-head 1–0, but Tanja Ostertag had been the form player, winning 3 of their last 5 on hard. Tanja Ostertag claimed a first win over Elizabeth Kaufman in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2005-05-16 | Mazatlan 10K | R32 | hard | Elizabeth Kaufman | 2-6 6-2 6-2 |