| Jun 9, 2026 | Roobol | ½–½ | Sielecki | Round 8: Roobol, Martin - Sielecki, Christof | Caro-Kann Defense: Tartakower Variation | |
| Jun 8, 2026 | Sielecki | ½–½ | Van der Werf | Round 7: Sielecki, Christof - Van der Werf, Mark | Ruy Lopez: Closed, Delayed Exchange | |
| Jun 7, 2026 | Dishman | ½–½ | Sielecki | Round 6: Dishman, Stephen - Sielecki, Christof | King's Indian Defense: Fianchetto Variation, Pterodactyl Variation | |
| Jun 6, 2026 | Sielecki | ½–½ | Hjartarson | Round 5: Sielecki, Christof - Hjartarson, Johann | King's Indian Defense: Orthodox Variation, Aronin-Taimanov Defense | |
| Jun 5, 2026 | Thorhallsson | ½–½ | Sielecki | Round 4: Thorhallsson, Throstur - Sielecki, Christof | Caro-Kann Defense: Exchange Variation | |
| Jun 4, 2026 | Sielecki | 1–0 | Fabiano | Round 3: Sielecki, Christof - Fabiano, Giuseppe Edoardo | English Opening: Anglo-Indian Defense, King's Knight Variation | |
| Jun 3, 2026 | Coste | 0–1 | Sielecki | Round 2: Coste, Thierry - Sielecki, Christof | Torre Attack: Fianchetto Defense | |
| Jun 2, 2026 | Sielecki | 1–0 | Brionne | Round 1: Sielecki, Christof - Brionne, Thierry | Dutch Defense: Raphael Variation | |
| Jun 1, 2026 | Sielecki | ½–½ | Degraeve | Round 9: Sielecki, Christof - Degraeve, Jean-Marc | King's Indian Defense: Orthodox Variation, Aronin-Taimanov Defense | |
| Oct 5, 2025 | Sielecki | 0–1 | Motuz | European individual senior chess championship 2025 - Open 50+, Rabac, Croatia | Ruy Lopez: Morphy Defense, Tarrasch Variation | |
| Oct 4, 2025 | Thorhallsson | 1–0 | Sielecki | European individual senior chess championship 2025 - Open 50+, Rabac, Croatia | Italian Game: Two Knights Defense, Modern Bishop's Opening | |
| Oct 3, 2025 | Sielecki | ½–½ | Holzke | European individual senior chess championship 2025 - Open 50+, Rabac, Croatia | English Opening: Symmetrical Variation | |
| Oct 2, 2025 | Van der Werf | ½–½ | Sielecki | European individual senior chess championship 2025 - Open 50+, Rabac, Croatia | King's Indian Defense: Orthodox Variation, Gligoric-Taimanov System | |
| Oct 1, 2025 | Sielecki | 1–0 | Bellia | European individual senior chess championship 2025 - Open 50+, Rabac, Croatia | English Opening: Anglo-Indian Defense, King's Knight Variation | |
| Sep 30, 2025 | Lacasa Diaz | ½–½ | Sielecki | European individual senior chess championship 2025 - Open 50+, Rabac, Croatia | King's Indian Defense: Orthodox Variation, Classical System | |
| Sep 29, 2025 | Sielecki | ½–½ | Dishman | European individual senior chess championship 2025 - Open 50+, Rabac, Croatia | Sicilian Defense: Accelerated Dragon, Maróczy Bind | |
| Sep 28, 2025 | Lasinskas | 0–1 | Sielecki | European individual senior chess championship 2025 - Open 50+, Rabac, Croatia | King's Indian Defense | |
| Sep 27, 2025 | Sielecki | 1–0 | Dejanovic | European individual senior chess championship 2025 - Open 50+, Rabac, Croatia | French Defense: Rubinstein Variation, Blackburne Defense | |
| Nov 2, 2024 | Dishman | ½–½ | Sielecki | Round 9: Dishman, Stephen - Sielecki, Christof | English Opening: Symmetrical Variation, Three Knights, Fianchetto Variation | |
| Nov 1, 2024 | Sielecki | ½–½ | Svenn | Round 8: Sielecki, Christof - Svenn, Gosta | French Defense: Tarrasch Variation, Closed Variation | |
| Oct 31, 2024 | Onem | 0–1 | Sielecki | Round 7: Onem, Cem - Sielecki, Christof | Indian Defense: King's Indian Variation, Fianchetto Variation | |
| Oct 30, 2024 | Sielecki | ½–½ | Nikolaidis | Round 6: Sielecki, Christof - Nikolaidis, Konstantinos | Sicilian Defense: Moscow Variation | |
| Oct 29, 2024 | Vinter-Schou | 1–0 | Sielecki | Round 5: Vinter-Schou, Uffe - Sielecki, Christof | Sicilian Defense: Kramnik Variation | |
| Oct 28, 2024 | Sielecki | ½–½ | Vehi Bach | Round 4: Sielecki, Christof - Vehi Bach, Victor Manuel | English Opening: Agincourt Defense | |
| Oct 27, 2024 | Issakainen | 0–1 | Sielecki | Round 3: Issakainen, Ari - Sielecki, Christof | Nimzo-Indian Defense: Classical Variation | |
| Oct 26, 2024 | Llopis de Aysa | ½–½ | Sielecki | Round 1: Llopis de Aysa, Manuel - Sielecki, Christof | Pirc Defense: Classical Variation | |
| May 15, 2024 | Sielecki | 1–0 | Mitchell | European Senior Team Chess Championship 2024 - Section 50 + | Pirc Defense: 150 Attack, Sveshnikov-Jansa Attack | |
| May 14, 2024 | Hjartarson | 1–0 | Sielecki | European Senior Team Chess Championship 2024 - Section 50 + | Sicilian Defense: Dragon Variation, Classical Variation | |
| May 13, 2024 | Sielecki | 1–0 | Frostick | European Senior Team Chess Championship 2024 - Section 50 + | Queen's Gambit Declined: Three Knights Variation | |
| May 10, 2024 | Sielecki | 1–0 | Dishman | European Senior Team Chess Championship 2024 - Section 50 + | Zukertort Opening | |
| May 7, 2024 | Sielecki | ½–½ | David | European Senior Team Chess Championship 2024 - Section 50 + | Caro-Kann Defense: Exchange Variation | |
| Dec 15, 2023 | Mazi | 1–0 | Sielecki | European Rapid Championship | Sicilian Defense: O'Kelly Variation, Maróczy Bind, Geller Line | |
| Dec 14, 2023 | Sielecki | 1–0 | Semjonovs | European Rapid Championship | English Opening: Symmetrical Variation, Four Knights Variation | |
| Dec 14, 2023 | Sielecki | 0–1 | Saric | European Rapid Championship | Zukertort Opening | |
| Dec 14, 2023 | Schoppen | 1–0 | Sielecki | European Rapid Championship | Catalan Opening: Open Defense | |
