Chess opening · ECO C42
Petrov's Defense: Three Knights Game
Against Petrov's Defense, 3.Nc3 skips the capture on e5 and simply guards the e4 pawn. White keeps the game calm and develops a second knight. Black now chooses how much symmetry to allow: 3...Nc6 turns the game into a Four Knights, 3...Bb4 puts pressure on the c3 knight, and 3...d6 builds a Philidor-like center.
- Rank by weighted share
- #95 of 159
Key moves
1. e4 e5 2. Nf3 Nf6 3. Nc3
- 3. Nc3The knight protects e4 so White no longer needs to grab on e5. It also covers d5, a square Black often wants for a pawn break, and keeps open plans with Bb5, Bc4 or d4.
Into the Four Knights with 3...Nc6
Black guards e5 with the other knight, and all four knights stand on their natural squares. The game is now a Four Knights Game, where White picks between Bb5, which puts pressure on the c6 knight, and d4, which opens the center.
The e4 pawn after 3...Bb4
Only the c3 knight guards e4. By attacking that knight, 3...Bb4 prepares ...Bxc3, which would remove the only guard of e4. White's replies keep the e4 pawn in mind, for example by castling and playing d3, or by taking on e5 at once, since nothing guards that pawn after 3...Bb4.
A mirrored Four Knights
3... Nc6 4. Bb5 Bb4 5. O-O O-O 6. d3 d6
Both kings are castled, so the bishops on b5 and b4 hit the knights on c6 and c3 without pinning them. Pawns on d3 and d6 secure e4 and e5, and White often breaks the symmetry next with Bg5 or Ne2.
Top replies by rating
Nc6 leads every band, and its share grows from 38 below 1200 to 74 at 2000 and up. Bb4 holds second place from 1200 up.
Related openings
Try it on the board. The first coached game and three analyses are free.