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

=Ruy Lopez Main Line=

Black has a number of options here:

Developing the f8-bishop to allow castling is a logical step.
 * 5...Be7 and
 * 5...Bc5 are both played; Bc5 carries more superficial attacking potential along the g1-a7 diagonal, but Black's natural plan of playing ...d6 will cut this bishop off from the defence of the kingside, plus it means White's natural plan of c3 followed by d4 will come with gain of tempo. Be7 is the most common move for these reasons. The bishop is not necessarily a bad piece on e7, where it supports the knight against any coming Bg5 ideas, and in the long term if Black is forced into playing ...g6 to evict a White knight from f5, it's useful to have the bishop available to redeploy to g7 via f8.


 * 5...b5 plans to develop the c8-bishop on b7 and the f8-bishop on c5, where they both aim at the kingside along adjacent diagonals. The difference between this move and the immediate ...Bc5 is that on ...Bc5 White can play c3 and get the bishop back to c2 in one move; here he must lose a tempo going via b3. Hence ...b5 is more common than ...Bc5.


 * 5...Nxe4 gives the a game a different flavour. Black tries to distract White from his development by snatching a pawn, leading to a more open position. As usual when a player grabs a pawn in the Ruy Lopez, trying to hold on to it turns out to be a bad idea.

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