After 1.e4 e5 2.Nf3 Black answers with 2...Nf6 and attacks the e4 pawn instead of defending e5. It is one of the most solid replies to 1.e4. You learn the main line after 3.Nxe5 d6, the answers to 3.d4 and 3.Nc3, what to do against the Cochrane Gambit, and the traps that punish Black for copying White. This is a intermediate opening course for Black (ECO C42) with 6 variations and 3 traps, written for players rated around 1150. Each move is explained and then drilled on a board; it is free.
Key ideas of Petroff Defence
After 3.Nxe5, do not copy White. Play 3...d6 first, chase the knight away, and only then take on e4.
Early in the game the e-file is dangerous for both kings. When a queen can reach e2 or e7, check what a discovered check could do before you move a knight off the file.
The black knight on e4 is strong, but White will attack it. Support it with ...d5, and be ready to trade it on c3 when White attacks it twice.
Develop quickly and castle short with ...Be7 or ...Bd6, ...Nc6 and ...O-O. A solid, symmetric centre gives White very few targets.
If White gives a knight for two pawns on f7, take it. Then bring your king to safety and develop. The extra piece matters more with every trade.
Variations you learn
Classical Main Line: 3.Nxe5 d6 and 5.d4 – 1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. d4 d5 …. The most important line. Black first kicks the knight with 3...d6, then takes on e4 and supports the knight with ...d5. White attacks the e4 knight with Bd3, c4 and Nc3, and Black trades it on c3 at the right moment. The position is solid and close to equal.
5.Nc3: castling on opposite sides – 1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. Nc3 Nxc3 …. White trades knights on c3, takes back with the d-pawn and castles long. White's plan is a pawn storm on the kingside. Black develops calmly, keeps the position closed and can castle on either side.
5.Qe2: the early queen trade – 1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. Qe2 Qe7 …. White pins the e4 knight with 5.Qe2. Black must answer 5...Qe7, and the queens soon come off. The game is quiet and equal. Black just needs to know the one forced move.
3.d4: the Steinitz Attack – 1. e4 e5 2. Nf3 Nf6 3. d4 Nxe4 4. Bd3 d5 5. Nxe5 Nd7 …. White opens the centre at once with 3.d4. Black takes on e4, supports the knight with ...d5, and trades White's strong knight on e5. Both sides castle short with a balanced game.
3.Nc3: into the Four Knights – 1. e4 e5 2. Nf3 Nf6 3. Nc3 Nc6 4. d4 exd4 5. Nxd4 Bb4 …. White defends e4 with 3.Nc3. Black answers 3...Nc6, and the game becomes a Four Knights Game. After 4.d4 Black takes, pins the c3 knight and builds a strong pawn on d5.
Cochrane Gambit: 4.Nxf7 – 1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nxf7 Kxf7 5. d4 Be6 …. White gives a knight for the f7 pawn to drag Black's king forward. Take the knight. Then walk the king to g8, develop and stay calm. Black gets a whole piece for two pawns and is better.
Traps
Copying White: 3...Nxe4? 4.Qe2 – After 3.Nxe5, copying White with 3...Nxe4 is a mistake. 4.Qe2 attacks the knight along the e-file. Even with the best defence, Black loses a pawn.
4...Nf6?? 5.Nc6+: the discovered check – In the copycat line, the natural retreat 4...Nf6 loses the queen. 5.Nc6+ opens a check from White's queen, and the knight attacks Black's queen at the same time.
3.Bc4 Nxe4 4.Bxf7+?: the empty check – Against 3.Bc4 Black can take on e4. If White grabs f7 with check, Black takes the bishop and hides the king on g8. Black ends up a piece for two pawns ahead.
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