Geller Gambit

The Geller Gambit, 5. e4, is White's sharpest reply to the pure Slav after 4...dxc4. Instead of 5. a4, which prevents ...b5 and recovers the pawn later, White builds a d4–e4 center at once and lets Black keep the extra pawn by expanding with ...b5. That reply is chosen in about half of all games. The usual continuation is 6. e5 Nd5 7. a4 e6 8. axb5 Nxc3 9. bxc3 cxb5. White uses the advanced e-pawn and extra space to attack on the kingside, while Black relies on the connected b- and c-pawns. In this line Black scores well, and computer analysis tends to side with Black. 6. Be2 is regarded as a better try. White castles quickly and then attacks the queenside pawns with moves such as b3.

The second most common reply is 5...Bg4, which develops the bishop with a pin instead of holding the pawn. 5...e6 is less frequent, and White scores well against it. The soundness of the sacrifice has been disputed for years, and as of 2005 the line was generally thought to favor Black. Current engines rate the position as roughly balanced. In online games White scores slightly better and draws are rare.