Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...a6/4. Ba4/4...Nf6/5. O-O/5...Nxe4

=Ruy Lopez, Riga Variation= The natural 6. Re1 is in fact a very minor sideline; not only does it commit the rook to the e-file unnecessarily, but it allows Black's knight to retreat to c5, forcing the exchange of the a4-bishop. If Bxc6 dxc6, Black is then doing rather well compared to the Exchange Variation as the bishop has lost a tempo and the disappearance of the centre pawns favours Black's bishop pair.

The immediate attempt to grab the pawn back with 6. Bxc6 and 7. Nxe5 is similar but even kinder to Black, who can now take the initiative by targeting the undefended white knight on e5.

Instead, White should control c5 with 6. d4 which tends to be a good developing move anyway. This threatens Black's e-pawn again, while the complications resulting from 6...exd4 are not considered too much to handle.

Theory table
. 1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Nxe4