Mark Merklein defeated Nenad Zimonjic 2-6 7-5 7-6 in the Halle q32 on grass. The upset overturned the form book — Nenad Zimonjic came in leading the head-to-head 1–0. Mark Merklein claimed a first win over Nenad Zimonjic in two meetings, narrowing the head-to-head to 1–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2003-07-21 | Indianapolis | Q16 | hard | Nenad Zimonjic | 2-6 6-0 6-1 |
Averages over each player's completed matches in the selected window. ATP, WTA & Challenger.