Marcos Ondruska defeated Joern Renzenbrink 7-5 6-2 in the Hamburg round of 32 on clay. The upset overturned the form book — Joern Renzenbrink came in leading the head-to-head 1–0. Marcos Ondruska claimed a first win over Joern Renzenbrink in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1993-09-27 | Basel | R32 | hard | Joern Renzenbrink | 3-6 6-3 7-5 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.