# Chess Opening Theory/1. e4/1...e6/2. d4/2...d5/3. Nc3/3...Nf6/4. Bg5/4...Be7

< Chess Opening Theory‎ | 1. e4‎ | 1...e6‎ | 2. d4‎ | 2...d5‎ | 3. Nc3‎ | 3...Nf6‎ | 4. Bg5
Classical variation
 a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h
Position in Forsyth-Edwards Notation(FEN)

rnbqk2r/ppp1bppp/4pn2/3p2B1/3PP3/2N5/PPP2PPP/R2QKBNR

# Classical variation

Because Nf6 is no longer pinned, Black threatens to win the e4-pawn.
The attempt to defend the e4-pawn, e.g. by 5.f3?! or 5.Bd3?!, will still lose the pawn, because White's Bg5 is not defended, so Black can simply play 5...Nxe4! and win a pawn (6. Bxe7 Nxc3 7. Bxd8 Nxd1 8. Bxc7 Nxb2 -/+).
That's why White either plays the e4-pawn to a safe square (Main Line - 5.e5), or eliminates an attacker of e4 (5.Bxf6). A safe alternative is a transposition to the Exchange Variation (5.exd5).

## Theory table

For explanation of theory tables see theory table and for notation see algebraic notation.

1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. Bg5 Be7
5
Main Line e5 =
1 Bxf6 =
2 exd5 =