Head to head
1
Clay
0
1
Grass
0
2
Carpet
3
Jakob Hlasek's wins on the left · Jan Siemerink's on the right · bar lengths share one scale
Momentum
Running lead across all meetings, oldest to newest (walkovers excluded).
All meetings (7)
| 1996 | Roland Garros | Clay | R64 | Jakob Hlasek | 6-2 1-6 6-3 7-6(3) |
| 1996 | Antwerp | Carpet | R32 | Jan Siemerink | 6-3 7-6(2) |
| 1995 | Copenhagen | Carpet | R16 | Jan Siemerink | 7-6(5) 6-7(5) 6-1 |
| 1991 | Moscow | Carpet | QF | Jakob Hlasek | 6-7(5) 6-2 6-2 |
| 1991 | Stockholm Masters | Carpet | R32 | Jakob Hlasek | 4-6 7-6(6) 7-6(4) |
| 1991 | Vienna | Carpet | R16 | Jan Siemerink | 6-7(6) 7-6(3) 6-3 |
| 1991 | Rosmalen | Grass | R16 | Jakob Hlasek | 7-6(4) 7-5 |
Methodology
Head-to-head totals and surface splits exclude walkovers (no match was played), which follows ATP convention — walkover meetings still appear in the match list. The momentum chart plots the running lead across all counted meetings, oldest to newest.