Ragozin Defense, Vienna Variation

With 5...dxc4, Black takes the c-pawn instead of breaking the pin with 5...h6 or reinforcing with 5...Nbd7. For now this leaves Black's c-pawns doubled, and it hands White the choice between quiet recovery and a full center. The most common reply is 6. e3, which prepares Bxc4 and leads to calmer play. The critical 6. e4 is the engine's top choice. It reaches the same position as the Vienna move order 4...dxc4 5. e4 Bb4 6. Bg5. After 6. e4 c5 7. Bxc4 cxd4 8. Nxd4, White's pieces and e-pawn dominate the center, but the pawn structure carries lasting weaknesses. Black seeks counterplay against c3 and e4. Fine–Euwe, AVRO 1938, is a well-known top-level example of the Vienna. A less frequent option is 6. Bxf6, giving up the bishop at once.

The engine considers the position close to balanced. In online games White scores noticeably better than Black, and draws are rare, which reflects how unbalanced the play tends to be.