4 games · 2021–2025 · 3 classical · 0 online
Posthuma 11 draws2 Matviishen
37.5% for Posthuma
Openings between them
| A50 | Queen's Indian Accelerated | 1 | 100.0% |
| B13 | Caro-Kann Defense: Exchange Variation | 1 | 50.0% |
| B30 | Sicilian Defense: Nyezhmetdinov-Rossolimo Attack | 1 | 0.0% |
| D11 | Slav Defense: Breyer Variation | 1 | 0.0% |
All games
| Matviishen, Viktor2540 | ½-½ | Posthuma, Joshua2392 | Marshall Summer Inv GMA | 2025 |
| Matviishen, Viktor2538 | 1-0 | Posthuma, Joshua2457 | CAN Transnational Classic | 2023 |
| Posthuma, Joshua2457 | 0-1 | Matviishen, Viktor2538 | CAN Transnational Rapid | 2023 |
| Matviishen, Viktor2512 | 0-1 | Posthuma, Joshua2256 | National Open 2021 | 2021 |