| Game |
| Result | Moves |
Year | Event/Locale | Opening |
| 26. N Weinstein vs M Diesen |
| 1-0 | 44 | 1974 | Las Vegas National op | B82 Sicilian, Scheveningen |
| 27. M Diesen vs J Kaplan |
| 1-0 | 38 | 1974 | Las Vegas National op | B83 Sicilian |
| 28. D Mabbs vs M Diesen |
| 0-1 | 32 | 1974 | Hastings Challengers 1973/74 | A45 Queen's Pawn Game |
| 29. M Diesen vs G Rol |
| 1-0 | 29 | 1974 | Hastings Challengers 1973/74 | B18 Caro-Kann, Classical |
| 30. M Diesen vs M Diedrick |
| 1-0 | 33 | 1974 | Pan-American Youth Championship | C97 Ruy Lopez, Closed, Chigorin |
| 31. M Diesen vs C B Jones |
| ½-½ | 40 | 1974 | Lone Pine | B29 Sicilian, Nimzovich-Rubinstein |
| 32. C Ghysels vs M Diesen |
| ½-½ | 34 | 1974 | International Junior Tournament | B83 Sicilian |
| 33. M Diesen vs D Proost |
| 1-0 | 41 | 1974 | International Junior Tournament | B43 Sicilian, Kan, 5.Nc3 |
| 34. J Weber vs M Diesen |
| ½-½ | 19 | 1974 | International Junior Tournament | D07 Queen's Gambit Declined, Chigorin Defense |
| 35. M Diesen vs C Hoi |
| ½-½ | 42 | 1974 | International Junior Tournament | A01 Nimzovich-Larsen Attack |
| 36. M Diesen vs A van der Wees |
| ½-½ | 42 | 1974 | International Junior Tournament | B29 Sicilian, Nimzovich-Rubinstein |
| 37. K Baumgaertner vs M Diesen |
| 1-0 | 33 | 1974 | International Junior Tournament | B33 Sicilian |
| 38. E Weinzettl vs M Diesen |
| 0-1 | 39 | 1974 | International Junior Tournament | A00 Uncommon Opening |
| 39. M Diesen vs A Machulsky |
| ½-½ | 44 | 1974 | International Junior Tournament | B59 Sicilian, Boleslavsky Variation, 7.Nb3 |
| 40. D Goodman vs M Diesen |
| ½-½ | 13 | 1974 | International Junior Tournament | A57 Benko Gambit |
| 41. M Basman vs M Diesen |
| ½-½ | 38 | 1974 | Hastings 1974/75 | C31 King's Gambit Declined, Falkbeer Counter Gambit |
| 42. M Diesen vs W Hartston |
| ½-½ | 23 | 1974 | Hastings 1974/75 | B44 Sicilian |
| 43. Andersson vs M Diesen |
| 1-0 | 57 | 1974 | Hastings 1974/75 | A15 English |
| 44. M Diesen vs Vaganian |
 | 0-1 | 54 | 1974 | Hastings 1974/75 | B05 Alekhine's Defense, Modern |
| 45. A Beliavsky vs M Diesen |
| 1-0 | 56 | 1975 | Hastings 1974/75 | C99 Ruy Lopez, Closed, Chigorin, 12...cd |
| 46. M Diesen vs M Stean |
| ½-½ | 22 | 1975 | Hastings 1974/75 | B51 Sicilian, Canal-Sokolsky (Rossolimo) Attack |
| 47. Miles vs M Diesen |
| 1-0 | 43 | 1975 | Hastings 1974/75 | A49 King's Indian, Fianchetto without c4 |
| 48. J Mestel vs M Diesen |
| ½-½ | 21 | 1975 | Hastings 1974/75 | C09 French, Tarrasch, Open Variation, Main line |
| 49. M Diesen vs A Planinc |
| ½-½ | 42 | 1975 | Hastings 1974/75 | B08 Pirc, Classical |
| 50. G Garcia Gonzalez vs M Diesen |
| 1-0 | 44 | 1975 | Hastings 1974/75 | A31 English, Symmetrical, Benoni Formation |
Kibitzing
