Openings · C42–C43

Petrov's Defence

Answer the attack on e5 by attacking e4: symmetry as a defence, and the most solid reply to 1.e4 there is.

1.e4 e5 2.Nf3 Nf6played as Black

The idea

2…Nf6 ignores the threat and makes one of its own. If White takes on e5, Black does not take back at once — he plays …d6 first, kicks the knight, and only then collects the pawn on e4 with everything defended.

Its reputation is dry, and that is the point: Black is choosing a game with few weaknesses over a game with chances for both sides. The Petrov punishes an opponent who needs to win and has nothing to attack — and it has a surprising number of short, sharp traps for anyone who thinks symmetry means safety.

Practise the line

You play Black; the other side answers on its own. Nothing here is saved or graded.

Your move 1 of 20/2

1.e4e5
2.Nf3Nf6

White is answering…

Common mistakes

Three that come up again and again below master level. Each is ordinary opening theory — a named trap, or the error every coach corrects — not a statistic, and not drawn from anybody's games.

Taking back on e4 immediately

1.e4 e5 2.Nf3 Nf6 3.Nxe5 Nxe4 4.Qe2 Nf6 5.Nc6+

The mistake: Answering 3.Nxe5 with 3…Nxe4 rather than 3…d6.
Why it costs: 4.Qe2 pins the knight to nothing in particular — until 4…Nf6 5.Nc6+ arrives. It is a discovered check that also attacks the queen, and Black loses her for a knight on move five. This is the oldest trap in the opening and it still works.
Instead: 3…d6 first, kicking the knight, and 4…Nxe4 after it moves. One move of patience is the whole difference.

The Stafford Gambit

1.e4 e5 2.Nf3 Nf6 3.Nxe5 Nc6 4.Nxc6 dxc6 5.d3

The mistake: Meeting 3.Nxe5 with 3…Nc6, hoping for a trap.
Why it costs: The gambit is a pawn for a set of one-move threats, and every one of them has a quiet answer — 5.d3 and 6.Be2 defuse the whole thing. Against anyone who declines to cooperate, Black is simply a pawn down with doubled pawns.
Instead: 3…d6. If you want an aggressive answer to 1.e4, play one that does not depend on your opponent being unfamiliar with it.

Grabbing the pawn on d4

1.e4 e5 2.Nf3 Nf6 3.d4 exd4 4.e5 Ne4 5.Qxd4 d5

The mistake: Taking on d4 instead of taking on e4.
Why it costs: 4.e5 gains a tempo on the knight and White recovers the pawn with a space advantage and a comfortable game — precisely the sort of position the Petrov is played to avoid.
Instead: 3…Nxe4, the main line. Black holds the extra piece for a moment and gives it back on his own terms after 4.Bd3 d5.

Try it on one of your own

The board above is for the line itself; this is for a game you played. Paste a game in this opening, or pull one from chess.com, and every move is graded against what the engine would have played. Open the board, read how the grading works, or go back to the other openings.