Head to head
1
Grass
0
1
Carpet
1
Clark Graebner's wins on the left · Nicholas Kalogeropoulos's on the right · bar lengths share one scale
All meetings (4)
| 1973 | Des Moines | Carpet | F | Clark Graebner | 7-5 4-6 6-4 |
| 1970 | Beckenham | Grass | SF | Clark Graebner | 6-1 6-3 |
| 1969 | Queen's Club | Grass | R128 | Clark Graebner | W/O |
| 1969 | Macon | Carpet | R32 | Nicholas Kalogeropoulos | 6-2 10-12 6-3 |
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.