C84 Ruy Lopez: Closed, Martinez Variation (6.d3)

ECO code C84 covers the Closed Ruy Lopez after 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O Be7, where Black declines to take on e4 and simply develops the bishop to prepare castling. The branch here is the Martinez Variation, 6.d3. Instead of the main-line rook move to e1, White defends the e4-pawn with a pawn and keeps the centre closed. The usual plan is slow manoeuvring: c3, Re1 and a knight route such as Nbd2–f1–g3, with a later d4 only when well prepared. Black typically answers with ...b5, ...d6 and ...O-O.