Jan Siemerink defeated Daniel Vacek 6-4 6-7 6-1 in the Rotterdam round of 32 on hard. The upset overturned the form book — Daniel Vacek came in leading the head-to-head 4–0, but Jan Siemerink had been the form player, winning 2 of their last 4 on hard. Jan Siemerink claimed a first win over Daniel Vacek in five meetings, narrowing the head-to-head to 4–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 1998-08-24 | Long Island | R16 | hard | Daniel Vacek | 6-1 4-6 6-3 |
| 1998-08-10 | Cincinnati Masters | R16 | hard | Daniel Vacek | 6-1 6-4 |
| 1997-03-03 | Rotterdam | R32 | hard | Daniel Vacek | 7-6 7-6 |
| 1995-05-08 | Hamburg | R32 | clay | Daniel Vacek | 4-1 |
Averages over each player's completed matches in the selected window (199 vs 180). ATP, WTA & Challenger.
Each player's serve crossed against the other's return, converted to expected hold of serve. Recent completed matches, ATP, WTA & Challenger. About