| Jul 3, 2026 | Nielsen | 0–1 | Johansson | Round 8: Nielsen, Peter - Johansson, Stefan 1957 | Zukertort Opening: Queen's Gambit Invitation | |
| Jul 2, 2026 | Olsson | 0–1 | Nielsen | Round 7: Olsson, Torgny - Nielsen, Peter | Indian Defense: Accelerated London System | |
| Jul 2, 2026 | Haddad | 0–1 | Nielsen | Round 6: Haddad, Tony - Nielsen, Peter | Sicilian Defense: Accelerated Dragon | |
| Jul 1, 2026 | Nielsen | 0–1 | Wiklund | Round 5: Nielsen, Peter - Wiklund, Robert | Sicilian Defense: Closed, Traditional | |
| Jun 30, 2026 | Andersson | 1–0 | Nielsen | Round 4: Andersson, Sven-Olof - Nielsen, Peter | Dutch Defense: Semi-Leningrad Variation | |
| Jun 29, 2026 | Nielsen | 0–1 | Dolata | Round 3: Nielsen, Peter - Dolata, Henryk | Nimzowitsch Defense: Scandinavian Variation, Advance Variation | |
| Jun 28, 2026 | Nielsen | * | W.O | Round 2: Nielsen, Peter - W.O | ? | |
| Jun 27, 2026 | Larsson | 1–0 | Nielsen | Round 1: Larsson, Per-Olov - Nielsen, Peter | Sicilian Defense: Hyperaccelerated Dragon | |
| Jul 31, 2025 | Nielsen | 0–1 | Boberg | Jonkoping Chess Festival 2025 - Standard Open | Caro-Kann Defense: Two Knights Attack | |
| Jul 30, 2025 | Hilali | 0–1 | Nielsen | Jonkoping Chess Festival 2025 - Standard Open | Dutch Defense | |
| Jul 29, 2025 | Nielsen | 0–1 | Eknor | Jonkoping Chess Festival 2025 - Standard Open | Bishop's Opening: Vienna Hybrid, Spielmann Attack | |
| Jul 28, 2025 | Oz | 0–1 | Nielsen | Jonkoping Chess Festival 2025 - Standard Open | Bogo-Indian Defense: Wade-Smyslov Variation | |
| Jul 28, 2025 | Nielsen | 0–1 | Jeyanth R | Jonkoping Chess Festival 2025 - Standard Open | Sicilian Defense: Closed | |
| Jul 27, 2025 | Hafthorsson | 1–0 | Nielsen | Jonkoping Chess Festival 2025 - Standard Open | Pirc Defense: Classical Variation | |
| Jul 26, 2025 | Nielsen | ½–½ | Berggren Torell | Jonkoping Chess Festival 2025 - Standard Open | Modern Defense: Pseudo-Austrian Attack | |
| Feb 25, 2023 | Nielsen | 0–1 | Nielsen | Danish CPH 2023 for 50+ and 65+ | East Indian Defense | |
| Feb 24, 2023 | Nielsen | 0–1 | Lindhard | Danish CPH 2023 for 50+ and 65+ | ? | |
| Feb 23, 2023 | Bohnstedt | 1–0 | Nielsen | Danish CPH 2023 for 50+ and 65+ | ? | |
| Feb 22, 2023 | Kiel Jensen | 1–0 | Nielsen | Danish CPH 2023 for 50+ and 65+ | ? | |
| Feb 21, 2023 | Nielsen | ½–½ | Jorgensen | Danish CPH 2023 for 50+ and 65+ | Sicilian Defense: O'Kelly Variation, Quiet System | |
| Feb 20, 2023 | Nielsen | 0–1 | Skovgaard | Danish CPH 2023 for 50+ and 65+ | Alekhine Defense: Modern Variation, Schmid Variation | |
| Feb 20, 2023 | Fjordside | 1–0 | Nielsen | Danish CPH 2023 for 50+ and 65+ | Indian Defense | |