Ruy Lopez: Berlin Defense, Improved Steinitz Defense

1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6 4.O-O d6

ECO C66

The Ruy Lopez: Berlin Defense, Improved Steinitz Defense is a chess opening line in the Ruy Lopez complex, reached after 1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6 4.O-O d6.

It is catalogued under code C66 in the Encyclopaedia of Chess Openings (ECO).

The defining move d6 is chosen by Black on move 4.

The Ruy Lopez: Berlin Defense, Improved Steinitz Defense is a line of the Ruy Lopez. The Ruy Lopez, also called the Spanish Game, is a chess opening that begins 1.e4 e5 2.Nf3 Nc6 3.Bb5. Read the complete Ruy Lopez guide: what it is, how to reach it, its main variations, how to play against it, and its history.

Study this line with a grandmaster

This position is covered in the Opening Tricks Hall of Fame course: a GM-authored repertoire you study move by move, then practice against a human-like AI opponent.

Every chess term used here is defined in the chess terms glossary. Browse all opening courses or the full ECO code index.