| Nov 22, 2025 | Nielsen | ½–½ | Zerafa | Round 9: Nielsen, Jon I Horni - Zerafa, Patrick | Ruy Lopez: Closed, Pilnik Variation | |
| Nov 21, 2025 | Nielsen | 1–0 | Owen | Round 8: Nielsen, Jon I Horni - Owen, Garth I | Sicilian Defense: Moscow Variation, Main Line | |
| Nov 19, 2025 | Nielsen | 1–0 | Konstantinidis | Round 6: Nielsen, Jon I Horni - Konstantinidis, Konstantinos | Ruy Lopez: Morphy Defense, Modern Steinitz Defense | |
| Nov 18, 2025 | Nielsen | 1–0 | Leardini | Round 5: Nielsen, Jon I Horni - Leardini, Mirko | Sicilian Defense: Alapin Variation, Barmen Defense | |
| Nov 17, 2025 | Belzo | ½–½ | Nielsen | Round 4: Belzo, Krzysztof - Nielsen, Jon I Horni | English Opening: Symmetrical Variation, Anti-Benoni Variation | |
| Nov 16, 2025 | Nielsen | 0–1 | Berend | Round 2: Nielsen, Jon I Horni - Berend, Elvira | Sicilian Defense: Delayed Alapin Variation, with e6 | |
| Nov 15, 2025 | Verdier | 0–1 | Nielsen | Round 1: Verdier, Patrice - Nielsen, Jon I Horni | Italian Game: Classical Variation, Giuoco Pianissimo | |
| Jul 11, 2023 | Jaroszewski | 1–0 | Nahalka | Piestany B | Italian Game: Classical Variation, Giuoco Pianissimo | |
| Jul 19, 2023 | Nielsen Jon I Horni | 1–0 | Garban Mario | Open A | Ruy Lopez: Morphy Defense | |
| Jul 17, 2023 | Nielsen Jon I Horni | 0–1 | Sharon Rafael | Open A | Caro-Kann Defense: Classical Variation, Lobron System | |
| Jul 17, 2023 | Skreko Igor | 0–1 | Nielsen Jon I Horni | Open A | Nimzo-Indian Defense: Classical Variation, Keres Defense | |
| Jul 16, 2023 | Farkas Gabor | 1–0 | Nielsen Jon I Horni | Open A | Rapport-Jobava System | |
| Jul 15, 2023 | Nielsen Jon I Horni | 1–0 | Balint Peter | Open A | Sicilian Defense: Kan Variation, Maróczy Bind, Réti Variation | |
| Jul 14, 2023 | Nielsen Jon I Horni | 1–0 | Kulich Daniel | Open A | Caro-Kann Defense: Classical Variation, Lobron System | |
| Jul 13, 2023 | Maryasin Boris | 1–0 | Nielsen Jon I Horni | Open A | Ruy Lopez: Closed, Bogoljubow Variation | |
| Jul 12, 2023 | Nielsen Jon I Horni | 0–1 | Kucharska Honorata | Open A | Sicilian Defense: O'Kelly Variation, Venice System | |
| Jul 11, 2023 | Marek Matyas | 1–0 | Nielsen Jon I Horni | Open A | Nimzo-Larsen Attack: Indian Variation | |
| Aug 28, 2022 | Nielsen | ½–½ | Elmi | Nordic Youth Chess Championships 2022: Class B - U17 | Sicilian Defense: Moscow Variation | |
| Aug 28, 2022 | Briem | 0–1 | Nielsen | Nordic Youth Chess Championships 2022: Class B - U17 | Queen's Indian Defense: Classical Variation, Traditional Variation, Nimzowitsch Line | |
| Aug 27, 2022 | Nielsen | 1–0 | Meskenas | Nordic Youth Chess Championships 2022: Class B - U17 | Ruy Lopez: Open | |
| Aug 27, 2022 | Polkki | ½–½ | Nielsen | Nordic Youth Chess Championships 2022: Class B - U17 | Queen's Gambit Declined: Exchange Variation, Positional Variation | |
| Aug 26, 2022 | Nielsen | 0–1 | Vainikka | Nordic Youth Chess Championships 2022: Class B - U17 | Ruy Lopez: Closed, Pilnik Variation | |
| Aug 26, 2022 | Ostlund | 1–0 | Nielsen | Nordic Youth Chess Championships 2022: Class B - U17 | Queen's Indian Defense: Petrosian Variation | |
