| Jul 23, 2026 | Oestmann | 1–0 | Ruchat | Round 10: Oestmann, Lukas - Ruchat, Blaise | Ruy Lopez: Closed, Keres Defense | |
| Jul 22, 2026 | Alsaleh | 0–1 | Oestmann | Round 9: Alsaleh, Eissa - Oestmann, Lukas | Sicilian Defense: Kan Variation, Knight Variation | |
| Jul 21, 2026 | Simon | 0–1 | Oestmann | Round 8: Simon, Ralf-Axel - Oestmann, Lukas | Benoni Defense: Benoni-Indian Defense, Kingside Move Order | |
| Jul 20, 2026 | Oestmann | 0–1 | Hornung | Round 7: Oestmann, Lukas - Hornung, Hans, Dr. | Ruy Lopez: Morphy Defense, Steinitz Deferred | |
| Jul 18, 2026 | Joly | 1–0 | Oestmann | Round 6: Joly, Fabrice - Oestmann, Lukas | Sicilian Defense: Staunton-Cochrane Variation | |
| Jul 17, 2026 | Oestmann | 0–1 | Ashwath Kaushik | Round 5: Oestmann, Lukas - Ashwath Kaushik | Sicilian Defense: Najdorf Variation, Amsterdam Variation | |
| Jul 16, 2026 | Oestmann | ½–½ | Erne | Round 4: Oestmann, Lukas - Erne, Raphael | Caro-Kann Defense: Advance Variation, Botvinnik-Carls Defense | |
| Jul 15, 2026 | Berezovskii | ½–½ | Oestmann | Round 3: Berezovskii, Arina - Oestmann, Lukas | Caro-Kann Defense: Exchange Variation | |
| Jul 14, 2026 | Oestmann | ½–½ | Kunz | Round 2: Oestmann, Lukas - Kunz, Andre | Caro-Kann Defense: Panov Attack, Modern Defense | |
| Jul 13, 2026 | Pleschke | 1–0 | Oestmann | Round 1: Pleschke, Julius Jonas - Oestmann, Lukas | Benoni Defense: Uhlmann Variation | |
| Mar 7, 2026 | Aeschbach | ½–½ | Oestmann | SGM | Benoni Defense: Benoni-Indian Defense, Kingside Move Order | |
| Jul 24, 2025 | Hoffmann | ½–½ | Oestmann | Biel Chess Festival 2025 MTO | English Opening: Anglo-Indian Defense | |
| Jul 23, 2025 | Oestmann | ½–½ | Schaffner | Biel Chess Festival 2025 MTO | Sicilian Defense | |
| Jul 22, 2025 | Jordan | ½–½ | Oestmann | Biel Chess Festival 2025 MTO | Caro-Kann Defense: Two Knights Attack, Mindeno Variation, Exchange Line | |
| Jul 21, 2025 | Oestmann | ½–½ | Cordes | Biel Chess Festival 2025 MTO | French Defense: Tarrasch Variation, Closed Variation | |
| Jul 19, 2025 | Heyl | ½–½ | Oestmann | Biel Chess Festival 2025 MTO | English Opening: King's English Variation, Four Knights Variation, Quiet Line | |
| Jul 17, 2025 | Oestmann | 0–1 | Kumbharathi | Biel Chess Festival 2025 MTO | Sicilian Defense: Najdorf Variation, Amsterdam Variation | |
| Jul 16, 2025 | Jordan | ½–½ | Oestmann | Biel Chess Festival 2025 MTO | Sicilian Defense: French Variation | |
| Jul 15, 2025 | Oestmann | 0–1 | Poeck | Biel Chess Festival 2025 MTO | Caro-Kann Defense: Accelerated Panov Attack, Modern Variation | |
| Jul 14, 2025 | Schlegel | 1–0 | Oestmann | Biel Chess Festival 2025 MTO | Sicilian Defense: French Variation | |
| Jul 24, 2024 | Haas | 0–1 | Oestmann | Biel Chess Festival 2024 | Benoni Defense: Fianchetto Variation | |
| Jul 23, 2024 | Oestmann | ½–½ | Yu | Biel Chess Festival 2024 | Sicilian Defense: Dragon Variation | |
| Jul 22, 2024 | Meshach | 1–0 | Oestmann | Biel Chess Festival 2024 | Sicilian Defense: Grand Prix Attack | |
| Jul 20, 2024 | Oestmann | 1–0 | Primbetova | Biel Chess Festival 2024 | French Defense: Tarrasch Variation, Chistyakov Defense | |
| Jul 17, 2024 | Lachausse | 0–1 | Oestmann | Biel Chess Festival 2024 | Sicilian Defense: Smith-Morra Gambit Accepted, Classical Formation | |
| Jul 16, 2024 | Oestmann | 1–0 | Kern | Biel Chess Festival 2024 | Caro-Kann Defense: Accelerated Panov Attack, Open Variation | |
| Jul 26, 2023 | Vihan | 0–1 | Oestmann | Biel International Chess Festival - Main Tournament | Benoni Defense: Taimanov Variation | |
| Jul 25, 2023 | Mamalis | 0–1 | Oestmann | Biel International Chess Festival - Main Tournament | Sicilian Defense: Closed | |
| Jul 24, 2023 | Oestmann | 0–1 | Khanabiev | Biel International Chess Festival - Main Tournament | Philidor Defense: Exchange Variation | |
| Jul 23, 2023 | Oestmann | 1–0 | Mirski | Biel International Chess Festival - Main Tournament | Sicilian Defense: Accelerated Dragon, Maróczy Bind | |
| Jul 21, 2023 | Wiesmann | 0–1 | Oestmann | Biel International Chess Festival - Main Tournament | King's Indian Attack: Symmetrical Defense | |
| Jul 20, 2023 | Oestmann | 1–0 | Arbinger | Biel International Chess Festival - Main Tournament | Pirc Defense: Classical Variation | |
| Sep 22, 2022 | Charaus | 0–1 | Oestmann | Hit Open 2022 | Indian Defense: Tartakower Attack | |
| Sep 21, 2022 | Oestmann | ½–½ | Budai | Hit Open 2022 | Ruy Lopez: Closed | |
| Sep 20, 2022 | Gregoric | 1–0 | Oestmann | Hit Open 2022 | Sicilian Defense: Snyder Variation | |
| Sep 19, 2022 | Oestmann | 1–0 | Bajo | Hit Open 2022 | Ruy Lopez: Closed, Anti-Marshall | |
| Sep 18, 2022 | Oestmann | ½–½ | Schloffer | Hit Open 2022 | Petrov's Defense: Nimzowitsch Attack | |
| Sep 18, 2022 | Krivenko | 1–0 | Oestmann | Hit Open 2022 | Sicilian Defense: French Variation | |
| Sep 17, 2022 | Alexandrova | 1–0 | Oestmann | Hit Open 2022 | King's Indian Defense: Fianchetto Variation, Yugoslav Variation | |
| Sep 17, 2022 | Zlatanovic | 0–1 | Oestmann | Hit Open 2022 | Indian Defense: Spielmann-Indian | |
| Sep 16, 2022 | Oestmann | ½–½ | Both | 26th HIT Open | Sicilian Defense: Kan Variation, Modern Variation | |
| Jul 25, 2022 | Oestmann | 1–0 | Andrzejewska | Biel Chess Festival 2024 | Ruy Lopez: Morphy Defense | |
| Jul 19, 2022 | Noh | ½–½ | Oestmann | Biel Chess Festival 2024 | Sicilian Defense: Kan Variation, Modern Variation | |
| Jul 18, 2022 | Oestmann | 1–0 | Mohr | Biel Chess Festival 2024 | Sicilian Defense: Dragon Variation, Yugoslav Attack, Panov Variation | |