Falkbeer Countergambit, Charousek Gambit

After 3...e4 the advanced pawn cramps White, taking f3 from the king's knight and blunting the plan of opening the f-file. The Charousek Gambit, 4. d3, challenges that pawn immediately. White accepts that the extra pawn on d5 will usually be returned, and in exchange opens lines for development before the wedge takes hold. Theory regards this as the reason the 3...e4 line declined in popularity. The engine rates the position as roughly balanced, and practical results are close to even.

The most common reply is 4...Nf6, which develops while aiming at d5. White then chooses between the Old Line, 5. Qe2, which pins the e4-pawn; the Keres Variation, 5. Nd2; and the Main Line, 5. dxe4 Nxe4 6. Nf3 Bc5 7. Qe2 Bf5, where Black relies on active pieces to compensate for the pawn. The immediate 4...Qxd5 is the second choice but scores noticeably worse for Black, while 4...exd3 is also played. The Morphy Defense arises by transposition from 2. Nc3, with 5...Bb4 6. Bd2 e3 offering further material.