| Game |
| Result | Moves |
Year | Event/Locale | Opening |
| 1. J R Phillips vs C Clemens |
| 0-1 | 30 | 1959 | World Junior Championship qual-2 | B92 Sicilian, Najdorf, Opocensky Variation |
| 2. C Clemens vs F Kuijpers |
| 1-0 | 27 | 1959 | World Junior Championship qual-2 | E25 Nimzo-Indian, Samisch |
| 3. H O Halen vs C Clemens |
| 0-1 | 31 | 1959 | World Junior Championship qual-2 | A07 King's Indian Attack |
| 4. C Clemens vs A Tomson |
| ½-½ | 16 | 1959 | World Junior Championship qual-2 | B76 Sicilian, Dragon, Yugoslav Attack |
| 5. R Primavera vs C Clemens |
| 0-1 | 40 | 1959 | World Junior Championship qual-2 | A60 Benoni Defense |
| 6. C Clemens vs D Grimshaw |
| 1-0 | 17 | 1959 | World Junior Championship qual-2 | C26 Vienna |
| 7. C Maalouf vs C Clemens |
| 0-1 | 39 | 1959 | World Junior Championship qual-2 | C45 Scotch Game |
| 8. C Clemens vs R Biever |
| 1-0 | 28 | 1959 | World Junior Championship qual-2 | A13 English |
| 9. C Clemens vs S Hamann |
| 0-1 | 37 | 1959 | World Junior Championship Final-A | C70 Ruy Lopez |
| 10. R Naranja vs C Clemens |
| 0-1 | 21 | 1959 | World Junior Championship Final-A | A22 English |
| 11. C Clemens vs C Bielicki |
| 1-0 | 41 | 1959 | World Junior Championship Final-A | B69 Sicilian, Richter-Rauzer Attack, 7...a6 Defense, 11.Bxf6 |
| 12. F Kuijpers vs C Clemens |
| 1-0 | 38 | 1959 | World Junior Championship Final-A | B92 Sicilian, Najdorf, Opocensky Variation |
| 13. C Clemens vs J Stefanov |
| ½-½ | 21 | 1959 | World Junior Championship Final-A | B36 Sicilian, Accelerated Fianchetto |
| 14. D E Rumens vs C Clemens |
| ½-½ | 27 | 1959 | World Junior Championship Final-A | B92 Sicilian, Najdorf, Opocensky Variation |
| 15. C Clemens vs W Erny |
| 1-0 | 37 | 1959 | World Junior Championship Final-A | E24 Nimzo-Indian, Samisch |
| 16. U Kuettner vs C Clemens |
| 0-1 | 51 | 1959 | World Junior Championship Final-A | E46 Nimzo-Indian |
| 17. C Clemens vs Parma |
| ½-½ | 41 | 1959 | World Junior Championship Final-A | E75 King's Indian, Averbakh, Main line |
| 18. C Clemens vs A Tomson |
| 0-1 | 33 | 1959 | World Junior Championship Final-A | B27 Sicilian |
| 19. J R Phillips vs C Clemens |
| 1-0 | 44 | 1959 | World Junior Championship Final-A | A45 Queen's Pawn Game |
| 20. S Nedeljkovic vs C Clemens |
| 1-0 | 47 | 1961 | European Team Championship | B68 Sicilian, Richter-Rauzer Attack, 7...a6 Defense, 9...Be7 |
| 21. C Clemens vs J Kozma |
| ½-½ | 52 | 1961 | European Team Championship | A15 English |
| 22. Forintos vs C Clemens |
| 1-0 | 29 | 1961 | European Team Championship | A11 English, Caro-Kann Defensive System |
| 23. F Ballbe Anglada vs C Clemens |
| 1-0 | 41 | 1961 | European Team Championship | B21 Sicilian, 2.f4 and 2.d4 |
| 24. D Minic vs C Clemens |
| 1-0 | 39 | 1961 | European Team Championship | B88 Sicilian, Fischer-Sozin Attack |
| 25. C Clemens vs Forintos |
| ½-½ | 70 | 1961 | European Team Championship | A22 English |
Kibitzing
