| Game |
| Result | Moves |
Year | Event/Locale | Opening |
| 26. I Anagnostou vs A Nielsen |
| ½-½ | 41 | 1954 | Amsterdam Olympiad Final-B | D32 Queen's Gambit Declined, Tarrasch |
| 27. V Maher vs A Nielsen |
| 0-1 | 74 | 1954 | Amsterdam Olympiad Final-B | D19 Queen's Gambit Declined Slav, Dutch |
| 28. A Nielsen vs Larsen |
 | 0-1 | 71 | 1955 | Danish Championship | A04 Reti Opening |
| 29. A Nielsen vs Larsen |
| 1-0 | 39 | 1955 | Nordic Championship | A16 English |
| 30. A Nielsen vs F Olafsson |
| ½-½ | 65 | 1955 | Nordic Championship | A16 English |
| 31. A Nielsen vs Larsen |
| 0-1 | 30 | 1956 | Copenhagen | A21 English |
| 32. F Roessel vs A Nielsen |
| 1-0 | 59 | 1956 | Copenhagen | C53 Giuoco Piano |
| 33. A Nielsen vs D Bertholdt |
| 1-0 | 61 | 1956 | Copenhagen | A14 English |
| 34. F Thorbergsson vs A Nielsen |
| 0-1 | 35 | 1956 | Copenhagen | E54 Nimzo-Indian, 4.e3, Gligoric System |
| 35. A Nielsen vs H Bouwmeester |
| ½-½ | 30 | 1956 | Copenhagen | A30 English, Symmetrical |
| 36. A Nielsen vs E Pedersen |
| ½-½ | 34 | 1956 | Copenhagen | A80 Dutch |
| 37. R Fuchs vs A Nielsen |
| 1-0 | 40 | 1956 | Copenhagen | C73 Ruy Lopez, Modern Steinitz Defense |
| 38. A Nielsen vs I Johannsson |
| 0-1 | 41 | 1956 | Copenhagen | B88 Sicilian, Fischer-Sozin Attack |
| 39. J Enevoldsen vs A Nielsen |
| 0-1 | 40 | 1956 | Copenhagen | E16 Queen's Indian |
| 40. G Noradounghian vs A Nielsen |
| 1-0 | 84 | 1956 | Moscow Olympiad qual-2 | B76 Sicilian, Dragon, Yugoslav Attack |
| 41. P Tumurbator vs A Nielsen |
| 0-1 | 39 | 1956 | Moscow Olympiad qual-2 | C07 French, Tarrasch |
| 42. A Nielsen vs J Sefc |
| 1-0 | 75 | 1956 | Moscow Olympiad Final-A | A12 English with b3 |
| 43. A Nielsen vs G Pfeiffer |
| ½-½ | 54 | 1956 | Moscow Olympiad Final-A | E19 Queen's Indian, Old Main line, 9.Qxc3 |
| 44. A Nielsen vs Ivkov |
| 0-1 | 34 | 1956 | Moscow Olympiad Final-A | A22 English |
| 45. A Nielsen vs Y Dobkin |
| 0-1 | 43 | 1956 | Moscow Olympiad Final-A | A06 Reti Opening |
| 46. A Nielsen vs Portisch |
| 0-1 | 63 | 1956 | Moscow Olympiad Final-A | C01 French, Exchange |
| 47. A Nielsen vs Larsen |
| ½-½ | 47 | 1959 | DEN-ch | A04 Reti Opening |
| 48. S From vs A Nielsen |
| 0-1 | 51 | 1960 | Danish Championship | A41 Queen's Pawn Game (with ...d6) |
| 49. A Nielsen vs K Blom |
| 1-0 | 32 | 1960 | Danish Championship | A10 English |
| 50. A Nielsen vs E Pedersen |
| 0-1 | 53 | 1960 | Danish Championship | A22 English |
Kibitzing
