Petrov's Defense
Black answers 2.Nf3 by counterattacking e4 instead of defending e5: the most solid defence to 1.e4 at the top level, and, with the Stafford Gambit, one of the trickiest at club level.
After 1.e4 e5 2.Nf3 Nf6 Black ignores the attack on e5 and hits White's own pawn. Named after the 19th-century Russian master Alexander Petrov (it is also called the Russian Game), analysed by Jaenisch and later played by Marshall, it became the drawing weapon of choice for Smyslov, Petrosian, Karpov, Kramnik and Caruana. Its reputation is dull, but the positions are anything but simple: the symmetry means one careless move is often all it takes. The first rule is famous: after 3.Nxe5, Black must play 3...d6 before taking on e4. The same family also contains the Stafford Gambit (3...Nc6), a dubious but trap-filled pawn sacrifice that Eric Rosen made hugely popular online.
The ideas in 7 positions
Click a card to see it on the board. 0/7 viewed
Choose your path
White chooses how to meet the Petrov: take on e5, strike in the centre with 3.d4, or develop with 3.Nc3.
Common mistakes, by level
Real patterns from club games. Every line is engine-checked; in the evals, plus is good for White.
These are the patterns worth knowing. For the full count, see the Petrov's Defense mistakes players make most often at each rating.
Middlegame plans
What to do once the book runs out.
Now make it stick
Reading is the easy part. Solve the real mistakes from this opening until the patterns fire by themselves.
Sources: Wikipedia: Petrov's Defence (history, main lines, Damiano and Nimzowitsch traps, Anand-Zapata 1988) · Wikipedia: Stafford Gambit (traps, refutations, Lowens-Stafford 1950) · Our own puzzle database: most frequent punished mistakes in Petrov's Defense (Lichess games, both players rated 1800+) · Stockfish 19, depth 20 on every mistake; every idea, variation and plan line checked move by move at depth 16
Counterattack e4 instead of defending e5
Move 1 of the line — press → or waitInstead of protecting e5 with ...Nc6, Black attacks White's e4 pawn. The position stays symmetrical and White gets no easy target like the Ruy Lopez pressure on e5 or the Italian pressure on f7. The downside is equally clear: if Black just copies White's moves, the symmetry eventually breaks in White's favour.