Two Knights Defense, Knight Attack, Normal Variation

The Normal Variation is Black's standard reply to the Knight Attack. Instead of defending f7 passively, 4...d5 strikes at the center and interposes a pawn on the c4-bishop's diagonal, so the knight on g5 no longer has a partner aimed at f7. The cost is a pawn, because White can and nearly always does take it with 5. exd5. Black's compensation lies in time and activity. The capture on d5 removes White's e-pawn from the center, and the bishop on c4 becomes a target for gains of tempo.

After 5. exd5 Black has to decide how to regain the initiative. The most respected answer is 5...Na5, the Polerio Defense, which harasses the bishop and leads to positions where White holds an extra pawn while Black enjoys a lead in development and freer piece play. The sharper tries 5...b5, the Ulvestad Variation, and 5...Nd4, the Fritz Variation, are seen less often. The natural recapture 5...Nxd5 is common among club players but exposes Black to two dangerous attacks: the knight sacrifice 6. Nxf7, known as the Fried Liver Attack or Fegatello, and the Lolli Attack, 6. d4. The choice at move five largely determines whether the game becomes a long positional fight over the extra pawn or an immediate tactical skirmish around Black's king.

White's alternatives to 5. exd5 are marginal. Taking with the bishop, 5. Bxd5, occurs in only about one game in a hundred, and Black scores clearly better against it. The immediate 5. Nxf7, which sacrifices the knight before the central tension is resolved, is about as rare and gives roughly balanced results in the database. The engine also lists 5. Bb5 and 5. Bb3 among its top choices, but these are hardly ever played in practice.

The engine rates the position as balanced, which reflects the view that Black's pawn sacrifice is sound. In the Lichess database the position is among the most frequently reached named openings. White wins slightly more often than Black, and draws are very rare, around three percent. These results reflect how forcing and unforgiving the lines after 5. exd5 tend to be at fast time controls.