Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. c3/3...Nf6/4. d4/4...Nxe4

Jaenisch counterattack C44 Jaenisch counterattack 4...Nxe4 4...Nxe4 takes White's undefended e4 pawn. This move is the main continuation at higher levels.57% of games in the Lichess master's database, 15% in the Lichess database. Black's knight on e4 also pressures White's f2 pawn, which will become a serious threat if Black can get their bishop to c5. How White recovers their pawn with or without allowing ...Bc5 determines how the game proceeds. Trade pawns? If White thinks they are simply trading pawns, because they have two attackers on e5 to Black's one defender, they are mistaken. As soon as White gives up control of c5, after 5. dxe5? or 5. Nxe5? Nxe5 6. dxe5, Black has ...Bc5!. Black's knight and bishop co-ordinate against f2, threatening to pick up a pawn and either fork the queen and rook or force White to lose castling rights. Black also threatens ...Qh4. Kick the knight The intermezzo 5. d5 is the main line and traditional Ponziani move. White's idea is to first kick the knight, and after it moves to recover the pawn safely without the threat of Bc5. After 5...Ne7 (main line), now White can capture the pawn 6. Nxe5 because Bc5 is not legal. After 6. Nxe5, Black's knight reroutes to g6: 6...Ng6 7. Nxg6 hxg6 Black gets the open h-file, and after 8. Qe2 Black is no longer in time for ...Bc5. If Black tries 5...Nb8 then 6. Nxe5 Bc5 is possible, but White can answer it with Nd3 to defend f2. (If 5...Na5? 6. c4 traps the knight.) However, 5. d5 also gives up control of c5 and so Black can choose to play 5...Bc5 immediately. This cunning knight sacrifice is the sharp Vukovic gambit, which brings Black the most practical success in the position. Anti-Vukovic The engine line is actually 5. Bd3. By keeping the pawn on d4, White prevents any complications involving ...Bc5. After 5...d5 defending the knight (5...Nf6?! gives up pressure on f2 and 6. dxe5 recovers the pawn with tempo) 6. Nxe5 White recovers the pawn and the game is even. Theory table 1 Jaenisch counterattack (mainline) 5. d5 Ne7 6. Nxe5 Ng6 7. Nxg6 hxg6 8. Qe2 Qe7 + Vukovic gambit accepted 5. ... Bc5 6. dxc6 Bxf2+ 7. Ke2 Bb6 8. Qd5 Nf2 9. Rg1 O-O 10. cxb7 Bxb7 11. Qxb7 - 5. ... ... 6. ... ... 7. ... ... 8. ... ... 9. cxb7 Bxb7 10. Qxb7 Nxh1 11. a4 - Vukovic gambit declined 5. ... ... 6. Be3? Bxe3 7. fxe3 Ne7 8. Nxe5 O-O 9. Nd2 Nf6 -- Anti-Vukovic 5. Bd3 d5 6. Nxe5 Bd6 7. Nc4 dxc4 8. Bxe4 5. ... ... 6. ... Nxe5 7. dxe5 Bc5 8. O-O O-O References See also Ponziani opening