# Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Nf6
## 3... Nf6 – Two Knights Defence

The Black Knight move 3... Nf6 announces the Two Knights; this aggressive defence results in open and often complex play. David Bronstein suggested that the term "Chigorin's Counterattack" would be more appropriate and this is certainly borne out with current theory. The Two Knights has been adopted as Black by many aggressive players including Chigorin and Keres, and World Champions Tal and Boris Spassky.

## Theory table

For explanation of theory tables, see theory table and for notation, see algebraic notation. .
    1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6
| | | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 |
| Traxler Counterattack or Wilkes-Barre Variation | 1 | Ng5 Bc5!? | Bxf7+ Ke7 | Bd5 Rf8 | O-O d6 | c3 Bg4 | Qb3 Bb6 | Bxc6 bxc6 | h3 h6 | +/= |
| Lolli Variation | 2 | ... d5 | exd5 Nxd5!? | d4 Bb4+ | c3 Be7 | Nxf7 Kxf7 | Qf3+ Ke6 | Qe4 Rf8 | f4 b5 | +/= |
| Fried Liver Attack | 3 | ... ... | ... ... | Nxf7!? Kxf7 | Qf3+ Ke6 | Nc3 Ncb4 | a3 Nxc2+ | Kd1 Nxa1 | Nxd5 Kd7 | +/= |
| Morphy Variation | 4 | ... ... | ... Na5 | d3 h6 | Nf3 e4 | Qe2 Nxc4 | dxc4 Bc5 | Nfd2 O-O | Nb3 Bg4 | = |
| Main Line Ng5 | 5 | ... ... | ... ... | Bb5+ c6 | dxc6 bxc6 | Be2 h6 | Nf3 e4 | Ne5 Bc5 | Ne5 Bc5 | ∞ |
| Steinitz Variation | 6 | ... ... | ... ... | ... ... | ... ... | ... ... | Nh3 Bd6 | d3 O-O | Nc3 Nd5 | ∞ |
| Bogoljubow Variation | 7 | ... ... | ... ... | ... ... | ... ... | Qf3 Rb8 | Bd3 h6 | Ne4 Nd5 | b3 g6 | ∞ |
| Ulvestad Variation | 8 | ... ... | ... b5 | Bf1 h6 | Nf3 Qxd5 | Nc3 Qe6 | Bxb5 Bb7 | Qe2 O-O-O | - - | ∞ |
| Fritz Variation | 9 | ... ... | ... Nd4 | c3 b5 | Bf1 Nxd5 | Ne4 Qh4 | Ng3 Bg4 | f3 e4 | cxd4 Bd6 | ∞ |
| Classical Variation | 10 | d4 exd4 | O-O Nxe4 | Re1 d5 | Bxd5 Qxd5 | Nc3 Qh5 | Nxe4 Be6 | Bg5 Bd6 | - - | = |
| Max Lange Attack | 11 | ... ... | ... Bc5 | e5 d5 | exf6 dxc4 | Re1+ Be6 | Ng5 Qd5 | Nc3 Qf5 | - - | +- |
| Max Lange Attack, Spielmann Variation | 11 | ... ... | ... ... | ... Ng4 | h3 Ngxe5 | Nxe5 Nxe5 | Re1 d6 | f4 0-0 | fxe5 dxe5 | = |
| Modern Variation | 12 | ... ... | e5 d5 | Bb5 Ne4 | Nxd4 Bc5 | Be3 Bd7 | Bxc6 bxc6 | O-O Bb6 | - - | = |
| | 13 | ... ... | ... Ne4 | Qe2 Nc5 | O-O Ne6 | Rd1 d5 | Bb5 Bc5 | c3 O-O | - - | = |
| | 14 | ... ... | ... Ng4 | O-O d6 | exd6 Bxd6 | Re1+ Be7 | h3 Nf6 | Nbd2 O-O | - - | = |
| Giuoco Piano by transposition | 15 | d3 Bc5 | - - | - - | - - | - - | - - | - - | - - | |
| | 16 | ... d5!? | exd5 Nxd5 | O-O Bc5 | Re1 O-O | Nxe5 Qh4 | Nf3 Qxf2+ | Kh1 Nf6 | - - | +/= |
| | 17 | ... Be7 | Bb3 O-O | O-O d6 | c3 Na5 | Bc2 c5 | Nbd2 Nc6 | Re1 Re8 | - - | = |
| Italian Four Knights Game by transposition | 18 | Nc3 Nxe4 | O-O Nxc3 | dxc3 Be7 | Qd5 O-O | Nxe5 Nxe5 | Qxe5 Bf6 | Qh5 c6 | - - | = |
| | 19 | O-O Nxe4 | Nc3 ... | ... f6 | Nh4 g6 | f4 Qe7 | Kh1 d6 | ... ... | - - | =+ |

## Statistics
### Estimated next move popularity

    d3 47%, Ng5 24%, d4 15%, Nc3 10%, O-O 2%, Qe2 1%
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## References

* The Two Knights Defence (1983) Yakov Estrin. ISBN 0-7134-3991-2.
* Kasparov, Garry, & Keene, Raymond 1989 Batsford chess openings 2. ISBN 0-8050-3409-9.
* Nunn's Chess Openings. 1999. John Nunn (Editor), Graham Burgess, John Emms, Joe Gallagher. ISBN 1-8574-4221-0.