Petrov's Defense: what should Black play?

In this position from the Petrov's Defense, Black faces immediate pressure against the central squares and must decide how to handle the advanced e5. The traditional and overwhelmingly popular choice is d6, which immediately kicks the knight and maintains solid equality. Alternatively, the engine rates Nc6 as an equally viable response, offering dynamic piece play at the cost of slight pawn compromises.

The Main Practical Continuation: d6

The standard move d6 dominates practical play, appearing in 70.7% of games (1.38M recorded). By driving the e5 back, Black secures room to develop and avoids early tactical complications, with White scoring 50.7% from this position. An illustrative continuation runs d6 Nf3 Qxe4+ Be2 Bf5 Na3, where Black recovers the central pawn with check and establishes active minor piece development. The engine evaluates this classical path at +0.90.

The Dynamic Alternative: Nc6

While less common, Nc6 is played in 2.6% of games (51K recorded) and shares the engine's top evaluation of +0.90. Instead of displacing the white knight with a pawn, Black introduces tactical counterplay against the center, resulting in a 49.8% scoring rate for White. Play often proceeds with the sequence Nc6 Nc3 Nxe5 dxe5 Qxe5 f4, leading to an open center where Black's queen actively contests the e5 square under tempo.

Less Effective Alternatives

Other moves leave Black with a more difficult defensive task. The immediate recapture Nxe4 accounts for 25.6% of recorded games (501K recorded) but yields a higher engine evaluation of +1.29, with White scoring 55.5% after Nxe4 Bd3 Nf6 O-O d6 Nf3. Flank tries such as c5 (+1.94, 21K recorded) and c6 (+2.45, 835 recorded) fail to challenge White's central space effectively, leading to comfortable advantages for White.