Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Nf6/4. Ng5/4...d5/5. exd5

Two knights defence C57 Two knights defence → 4. Ng5 → 4...d5 5. exd5 Taking the pawn is an automatic move as other moves lose material. Black has a selection of interesting moves leading to diverse tactical positions. The classical way to play, and one of the most popular continuations in amateur games, is 5...Nxd5?!. However, this is now known to be inferior. It allows 6. Nxf7+!, an audacious knight sacrifice known as the fried liver where Black's king is hounded into the centre of the board, or 6. d4, the Lolli attack and Bobby Fischer's preferred line. 5...Na5, the Polerio variation, is the most serious continuation and main line today. Black counterattacks the bishop, and the line continues 6. Bb5+ c6 7. dxc6 bxc6 8. Bd3 Nd5 9. Nf3 Bd6 10. O-O. White may be ahead a pawn, but Black is considered equal with more active pieces. 5...b5!? is the Ulvestad variation. Black offers a pawn to deflect the bishop from control of d5 and pressure of f7, so that they may retake on d4 with the queen. This works out very well for Black if White accepts the sacrifice, but not so well if White knows the surprising refutation 6. Bf1!. 5...Nd4!?, the Fritz variation, gets the knight out from under the gun. After 6. c3 b5, this usually leads to a trade of minor pieces but White is still a pawn ahead: 8. cxd4 Qxg5 9. Bxb5+ Kd8 ++. Theory table 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5. exd5 5 6 7 8 Main Line exd5Na5 Bb5+c6 dxc6bxc6 Be2h6 ∞ Bogoljubov Variation ...... ...... ...... Qf3?!Rb8 ∞ Ulvestad Variation ...b5 Bf1h6 Nxf7Kxf7 dxc6Bc5 += Fritz Variation ...Nd4 c3b5 Bf1Nxd5 Ne4Qh4 += Lolli Variation ...Nxd5!? d4Bb4+ c3Be7 Nxf7Kxf7 += Fried Liver Attack ...... Nxf7!!Kxf7 Qf3!Ke6 Nc3Nb4 ∞ References Two Knights Defence