| Game |
| Result | Moves |
Year |
Event/Locale | Opening |
| 1. Pilnik vs G Mazzoni |
| 0-1 | 45 |
1954 |
Paris | B18 Caro-Kann, Classical |
| 2. G Mazzoni vs O'Kelly |
| 1-0 | 52 |
1962 |
Paris 6263 | B90 Sicilian, Najdorf |
| 3. G Mazzoni vs B Huguet |
| 0-1 | 33 |
1962 |
Paris 6263 | B87 Sicilian, Fischer-Sozin with ...a6 and ...b5 |
| 4. C Kottnauer vs G Mazzoni |
| ½-½ | 33 |
1962 |
Paris 6263 | A00 Uncommon Opening |
| 5. C Boutteville vs G Mazzoni |
| ½-½ | 55 |
1962 |
Paris 6263 | C02 French, Advance |
| 6. G Mazzoni vs J Penrose |
| 0-1 | 28 |
1963 |
Enschede zt | E67 King's Indian, Fianchetto |
| 7. Gligoric vs G Mazzoni |
| 1-0 | 26 |
1963 |
Enschede zt | E44 Nimzo-Indian, Fischer Variation, 5.Ne2 |
| 8. W Heidenfeld vs G Mazzoni |
| 0-1 | 20 |
1963 |
Enschede zt | B23 Sicilian, Closed |
| 9. K Darga vs G Mazzoni |
| 1-0 | 28 |
1963 |
Enschede zt | B92 Sicilian, Najdorf, Opocensky Variation |
| 10. J Durao vs G Mazzoni |
| ½-½ | 42 |
1963 |
Enschede zt | B93 Sicilian, Najdorf, 6.f4 |
| 11. S Tatai vs G Mazzoni |
| 1-0 | 39 |
1963 |
Enschede zt | C77 Ruy Lopez |
| 12. G Mazzoni vs J Kupper |
| 0-1 | 38 |
1963 |
Enschede zt | B32 Sicilian |
| 13. Aitken vs G Mazzoni |
| ½-½ | 41 |
1963 |
Enschede zt | C78 Ruy Lopez |
| 14. J Llado Lumbera vs G Mazzoni |
| 0-1 | 41 |
1963 |
Enschede zt | B52 Sicilian, Canal-Sokolsky (Rossolimo) Attack |
| 15. G Mazzoni vs G Philippe |
| 1-0 | 41 |
1963 |
Enschede zt | C81 Ruy Lopez, Open, Howell Attack |
| 16. G Mazzoni vs O'Kelly |
| 0-1 | 36 |
1963 |
Ch Paris (open) | C16 French, Winawer |
| 17. G Mazzoni vs J Boey |
| 0-1 | 50 |
1963 |
Enschede zt | C92 Ruy Lopez, Closed |
| 18. G Mazzoni vs Filip |
 | 0-1 | 38 |
1963 |
Enschede zt | A62 Benoni, Fianchetto Variation |
| 19. G Mazzoni vs B Simonovic |
| 1-0 | 22 |
1963 |
Paris | B97 Sicilian, Najdorf |
| 20. G Mazzoni vs A Pomar-Salamanca |
| 0-1 | 50 |
1963 |
Enschede zt | B70 Sicilian, Dragon Variation |
| 21. G Mazzoni vs L Lengyel |
| 0-1 | 32 |
1963 |
Enschede zt | B43 Sicilian, Kan, 5.Nc3 |
| 22. G Mazzoni vs C Chaude de Silans |
| 1-0 | 41 |
1964 |
Bordeaux op | C91 Ruy Lopez, Closed |
| 23. A Prameshuber vs G Mazzoni |
| 1-0 | 34 |
1966 |
Havana ol (Men) fin-B | A48 King's Indian |
| 24. G Mazzoni vs Z Vranesic |
| 1-0 | 47 |
1966 |
Havana ol | B14 Caro-Kann, Panov-Botvinnik Attack |
| 25. G Mazzoni vs Larsen |
| 0-1 | 54 |
1966 |
Le Havre | B61 Sicilian, Richter-Rauzer, Larsen Variation, 7.Qd2 |