Sabine Appelmans defeated Steffi Graf 6-3 7-6 in the Hanover quarter-final on carpet. The upset overturned the form book — Steffi Graf came in leading the head-to-head 1–0. Sabine Appelmans claimed a first win over Steffi Graf in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1991-05-27 | Roland Garros | R16 | clay | Steffi Graf | 6-2 6-2 |