Colle System · A04

Rhamphorhynchus Variation

1. Nf3 c5 2. e3 g6 3. d4 Bg7 4. 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. White develops with Nf3, e3, Bd3, c3, and 0-0, then plays for the e3-e4 break to free the position.

The first 4 moves, explained

• 1. Nf3 Develops the knight to f3, eyeing d4 and e5. Theory calls this the Zukertort Opening.
• 1... c5 Fights for d4 from the flank - contesting the centre without committing a centre pawn. Theory calls this the Sicilian Invitation.
• 2. e3 Supports the centre, adding control of d4.
• 2... g6 Prepares the fianchetto: the bishop will take the long diagonal via g7.

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