| 26 ago 2026 | Behrens, Harald 2184 | Kolthoff, Siegmund 2068 | ½-½ | D02 Apertura de Peón de Dama: Symmetrical Variation, Pseudo-Catalan | 23. Rheinland-Pfalz Senioren Open | 13 | Ver |
| 23 ago 2026 | Heck, Norbert 2231 | Kolthoff, Siegmund 2068 | 1-0 | E05 Apertura Catalana: Open Defense, Classical Line | 23. Rheinland-Pfalz Senioren Open | 52 | Ver |
| 12 jul 2026 | Migl, Dieter 2157 | Kolthoff, Siegmund 2065 | ½-½ | D01 Ataque Richter-Veresov: Two Knights System | 34. Off. Senioren-LEM Sachsen-Anhalt | 65+ | 10 | Ver |
| 4 jul 2026 | Okrajek, Alexander 2199 | Kolthoff, Siegmund 2065 | ½-½ | A37 Apertura Inglesa: Symmetrical Variation, Botvinnik System Reversed, with Nf3 | 34. Off. Senioren-LEM Sachsen-Anhalt | 65+ | 9 | Ver |