Chess Opening Theory/1. d4/1...g5

Perhaps the worst possible reply to 1. d4 is 1...g5??. Against 1. e4, 1...g5? is bad because it fails to contest White's centre and weakens Black's kingside. Against 1. d4 it has the added disadvantage of sacrificing the pawn immediately.

2. Bxg5, accepts the gambit while developing a piece. A common mistake is 2...f6?, thinking to kick White's "overextended" bishop: unfortunately this weakens Black's kingside too much and the bishop is unassailable: 3. e4 fxg5?? 4. Qh5#. Instead, ideas for Black include increasing pressure on d4 with ...Bg7, making use of the square opened by playing 1...g5, and ...c5. Black can try for counter-play using the semi-open g-file with ...Rg8. Overall, Black does not have sufficient compensation for the pawn.

2. e4 is an alternative. White prioritises taking space in the centre and opens more lines for their queen and king's bishop to develop. This transposes to the Borg defence 1. e4 g5?? 2. d4. In this line Black can play ...Bg7 and ...c5, but also has the sly idea of 2...g4?! 3. Qxg4, where Black hopes to gain time on White's queen while attacking the centre.

The name "Borg" comes from the reverse of "Grob". The Grob, considered to be one of the worst starting moves, is 1. g4, therefore when Black begins with the g-pawn, 1. e4 g5?, they have played the "reverse Grob" i.e. the "Borg". When ...g5 is played after 1. d4, it is a gambit as it immediately offers the pawn to 2. Bxg5.

It is rare in tournament chess. An early recorded outing was in 1987, where the gambit was declined with 2. Nc3.^[1] It is most often seen as a surprise weapon in blitz chess.^[2]

For explanation of theory tables, see theory table and for notation, see algebraic notation.

1. d4 g5

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