Czech Variation

The Czech Variation is generally treated as the main line of the Slav. White's 5. a4 rules out ...b5 and prepares e4 followed by Bxc4. Black's 5...Bf5 prevents that center grab and brings the queen's bishop out before ...e6. The pawn on c4 now blocks the Qb3 idea that makes an early ...Bf5 dubious elsewhere in the Slav. White is a pawn down for the moment, so the play centers on how White wins it back. Engines rate the position as roughly balanced, and online results are close to even.

The most common choice is 6. e3, the Classical System. White recaptures with the bishop, castles and prepares e4. After 6...e6 7. Bxc4 Bb4 8. O-O the line is called the Dutch Variation, and 6...Na6 is the Lasker Variation. The more ambitious 6. Ne5, the Krause Attack, recaptures with the knight and leads to sharper positions. Its branches include 6...e6, the Wiesbaden Variation, and the Carlsbad Variation, 6...Nbd7 7. Nxc4 Qc7 8. g3 e5. With 6. Nh4, the Bled Attack, White targets the f5-bishop before recovering the pawn. It can transpose into Classical lines. 6. Bg5 is a less common alternative.