Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Nf6/4. d4/4...exd4

Black is a pawn up but has a number of weaknesses: the square e5, the Knight on f6 that can be pinned, and the weak f7 square. This all adds up to giving White a number of options:

• 5. O-O the classical variation.
• 5. e5 the modern variation.
• 5. Ng5 a misguided direct attack on f7.
• 5. Nxd4 rather normal move.
• 5. Bg5 pinning the Knight, but the pin can soon be undone, leaving no advantage for White.
• 5. Qe2 this supports e5, although e5 can be played immediately anyway.
• 5. c3 fails to 5...Nxe4 where Black has the nice d5 available and time to block any pins on the e-file against the King.

1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4.d4 exd4

• Nunn's Chess Openings. 1999. John Nunn (Editor), Graham Burgess, John Emms, Joe Gallagher. ISBN 1-8574-4221-0.

• Kasparov, Garry, & Keene, Raymond 1989 Batsford chess openings 2. ISBN 0-8050-3409-9.