Ruy Lopez, Main Line

	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

Common moves:
5. O-O - Main Line
5. Nc3 - Spanish Four Knights
5. d3 - Anderssen Variation
5. Qe2 - Wormald Attack

Black's move 4...Nf6 threatens White's e-pawn. White may defend it directly with

• 5.d3, the Anderssen Variation or
• 5.Nc3 transposing to the Four Knights, Spanish Variation

but both moves interfere with White's natural plan of playing c3 and d4. Without playing c3 and d4 to create some central tension it will be difficult to generate open files for the rooks; additionally White's star attacker currently residing on a4 is liable to get swapped off if it does not have the option of retreating to c2.

• 5.Qe2, the Wormald Attack, retains the option of c3 and d4, and introduces the medium-term plan of shifting the king's rook across to d1 in a single move after White castles kingside. The downside is that it places the queen on a file that's very likely to get opened, or at least half-opened. Put your rooks on open files and your queen on a closed one!

The main line, and a more subtle way of maintaining material equality, is 5. O-O, after which Black can grab a pawn but cannot hold on to it.

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 5. O-O   (Morphy's Defence Main Line)

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 5. d3   (Anderssen 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 5. Nc3   (Spanish Four Knights /Tarrasch 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 5. Qe2   (Wormald Attack)

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 5. d4   (Mackenzie-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 5. Bxc6   (Bayreuth Variation)

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

1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6

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Wikipedia has related information at Ruy Lopez

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