Classical Variation, Modern Main Line

This line of the Classical Variation usually arises through the Berlin move order 3...Nf6 4. O-O Bc5. Black declines the Zukertort Gambit (5. c3) by castling instead of taking on e4. White gains a broad center with tempo through 6. d4, and after 6...Bb6 pins the f6 knight with 7. Bg5. Black most often questions the bishop with 7...h6, and 7...d6 is the main alternative. Releasing the tension with 7...exd4 is rare and scores poorly. Engines give White a slight edge.