Advance Variation, Milner-Barry Gambit, Main Line

With 8. O-O White completes kingside development and leaves d4 to its fate. Black's 7...Bd7 has removed the Bb5+ trick, so the pawn can now be taken, and 8...Nxd4 is the overwhelming choice. After 9. Nxd4 Qxd4 10. Nc3 White is a pawn down but ahead in development, with the knight eyeing b5 and d5 and the bishop aiming at the kingside. Accepting a second pawn with 10...Qxe5 leaves Black's queen exposed on the open central files: 11. Re1 gives White a strong initiative, as in 11...Qb8 12. Nxd5 or 11...Qd6 12. Nb5. The Sørensen Variation, 8...Nxd4 9. Ng5, is a separate way of handling the gambit.

Black can also decline. The quieter 8...Nge7 is rare and scores poorly. The less common 8...Nb4 has produced good results for Black in online games. The engine assesses the position after 8. O-O as roughly balanced, and play in the critical lines is sharp and concrete, with each side relying heavily on accurate preparation.