Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...a6/4. Ba4/4...Nf6/5. O-O/5...Be7

If Black had chosen to capture White's e-pawn on the previous move (5...Nxe4, the Open Spanish), White could have recovered the pawn tactically by exploiting Black's multiple vulnerabilities on the half-open e-file. 5...Be7 removes one of these vulnerabilities by guarding Black's king. Consequently, Black now threatens to win the pawn outright via 6...b5 (removing White's remaining tactical opportunity to win Black's e-pawn in exchange for his own) 7. Bb3 Nxe4.

How does White answer this threat? Usually with 6. Re1. With White's e-pawn finally defended, the threat of Bxc6 & Nxe4 is now critical, as Black can no longer recover the pawn tactically with ...dxc6 & ...Qd4.

6. Qe2 is an alternative, the Worrall Attack.^[1] As in the 5. Qe2 line the plan is to hold e4 with the queen and move the rook to d1 in preparation for d2-d4. Again this has the drawback of putting the queen on the file most likely to be opened by Black.

Other ways of defending, 6. Nc3, the Morphy attack or 6. d3, the Martinez variation, interfere with White's plan of c3 and d4.

White can also opt for 6. Bxc6!?, the fantastically named Delayed Exchange Ruy Lopez Deferred (deferred with 4. Ba4 and delayed with 5. O-O, or something like that). Compared to the main line of the Exchange Variation, White has lost a tempo, but Black can no longer play ...f6 to hold the e-pawn. White can also argue that Black's bishop on e7 is awkwardly developed compared to the normal Exchange Variation.

6. d4 is the Centre attack.

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 5. O-O Be7

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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.