| Game |
| Result | Moves |
Year | Event/Locale | Opening |
| 1. J Kupper vs Keres |
  | 0-1 | 41 | 1961 | Zuerich | C73 Ruy Lopez, Modern Steinitz Defense |
| 2. J Kupper vs L Prins |
| ½-½ | 41 | 1962 | Clare Benedict Cup | C73 Ruy Lopez, Modern Steinitz Defense |
| 3. J Kupper vs Gligoric |
| ½-½ | 57 | 1963 | Enschede Zonal | C73 Ruy Lopez, Modern Steinitz Defense |
| 4. J Kupper vs J Llado Lumbera |
| ½-½ | 30 | 1963 | Enschede Zonal | C73 Ruy Lopez, Modern Steinitz Defense |
| 5. J Kupper vs A Paidousis |
| 1-0 | 41 | 1964 | Tel Aviv Olympiad Final-C | C73 Ruy Lopez, Modern Steinitz Defense |
| 6. J Kupper vs A Medina Garcia |
| ½-½ | 44 | 1972 | Clare Benedict Cup | C73 Ruy Lopez, Modern Steinitz Defense |
Kibitzing
