Lars Koslowski defeated Rudiger Haas 6-1 4-6 7-5 in the Germany 1 Masters 1 qualifying round on carpet. The upset overturned the form book — Rudiger Haas came in leading the head-to-head 1–0. Lars Koslowski claimed a first win over Rudiger Haas in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1991-02-03 | Germany 1 Masters 3 | R32 | carpet | Rudiger Haas | 6-4 2-6 7-6 |