Spanish Variation, Double Spanish

The move 4...Bb4 copies White's idea on the other wing. Just as the bishop on b5 bears on the c6 knight that guards e5, Black's bishop pins the c3 knight that protects e4. The line is also called the Double Ruy Lopez, since the position is a Ruy Lopez with ...Nf6, Nc3 and ...Bb4 added. It is the principal answer to 4. Bb5 at master level. Play tends to stay symmetrical for several more moves, most often through 5. O-O O-O, which leads to the named branches listed under the Spanish Variation. When White delays castling, both sides usually castle soon afterward and transpose, although this is not forced.

In online games the immediate exchange 5. Bxc6 is the most frequent choice. It settles the structure at once instead of waiting for the castled lines. 5. d3 and 5. O-O follow, each about equally common. Engines prefer 5. O-O, then 5. d3 and 5. Ba4, and rate the position as balanced. White scores slightly better than Black in practice, and draws are uncommon in online play.