Daniel Vacek defeated Jan Siemerink 6-1 6-4 in the Cincinnati Masters round of 16 on hard. The result followed the form book — Daniel Vacek came in leading the head-to-head 3–1, defending last year's round of 64. Daniel Vacek extended 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 |
| 1997-03-03 | Rotterdam | R32 | hard | Daniel Vacek | 7-6 7-6 |
| 1995-05-08 | Hamburg | R32 | clay | Daniel Vacek | 4-1 |
| 1993-02-22 | Rotterdam | R32 | hard | Jan Siemerink | 6-4 6-7(4) 6-1 |
Averages over each player's completed matches in the selected window (136 vs 151). 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