Modern Defense · A04

Semi-Averbakh Variation, Pterodactyl Variation Accepted

1. Nf3 g6 2. d4 Bg7 3. e4 d6 4. c4 c5 5. dxc5 Qa5+

An early pawn trade leaves the c-file as Black's avenue and the d-file as White's - both sides get real winning chances down their own file. White is up material out of the opening - Black is banking on activity to show for it. Black's kingside bishop takes the long diagonal. ...g6 before anything: maximum flexibility, the g7 bishop as the anchor, and the pawn breaks chosen only after White commits.

The first 4 moves, explained

• 1. Nf3 Develops the knight to f3, eyeing d4 and e5. Theory calls this the Zukertort Opening.
• 1... g6 Prepares the fianchetto: the bishop will take the long diagonal via g7. Theory calls this the Kingside Fianchetto.
• 2. d4 Stakes a claim in the centre, controlling e5, and frees the bishop and queen.
• 2... Bg7 Fianchettoes the bishop onto the long diagonal, pressuring d4 and e5 from a distance.

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