Ruy Lopez: Berlin Defense, Improved Steinitz Defense
The Improved Steinitz Defense is 4.O-O d6 in the Berlin, where Black protects e5 with the d-pawn instead of taking on e4. White aims for d4 and central space, while Black keeps a compact but slightly passive setup with ...Bd7 and ...Be7.
- Moves
- 1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6 4.O-O d6
- ECO
- C66
- Engine
- +0.59 · a slight edge for White (Stockfish 17.1, depth 20)
- Played
- 2,013 games in our lichess sample
- White scores
- 54.3%
Key ideas for both sides
White
- Play d4 at once, as in the top engine line, and recapture with the knight after ...exd4.
- Use Nc3 and Re1 to back up e4 and keep the space edge in the center.
- Trade on c6 with Bxc6 when it ruins Black's pawns, then push d4.
- A slower Re1, h3 and c3 build-up keeps the Spanish bishop for a long game.
Black
- After d4, take with ...exd4 and play ...Bd7, ...Be7 and castling for a compact position.
- Unpin with ...Bd7 so the c6 knight is not a target for Bxc6 and Nxe5 tricks.
- Look for ...a6 and ...b5 to gain queenside space if White plays slowly.
Plans and pawn structure
White has more space after d4 and usually keeps the e4 pawn as a strong center point. Black gives up the center with ...exd4 but gets a sturdy setup with knights on c6 and f6, bishops on d7 and e7, and the king castled. White builds with Nc3, Re1 and possibly f4, while Black looks for ...Re8, ...Bf8 and pressure on e4. The game is about White's space against Black's lack of weaknesses.
What the engine plays from here
Stockfish 17.1 at depth 20 rates the position +0.59: a slight edge for White. Its three top choices for White:
- +0.59 5.d4 exd4 6.Nxd4 Bd7 7.Nc3 Be7
- +0.46 5.Nc3 a6 6.Bxc6+ bxc6 7.d4 Nd7
- +0.39 5.Re1 Be7 6.h3 O-O 7.c3 a6
Pawns, from White's side.
How it scores on lichess
2,013 rated lichess games reached this position; White scored 54.3%.
Light: White wins. Grey: draws. Dark: Black wins. About the sample.
Where it goes next
- Berlin Defense, Closed Showalter Variation5.d4 · rare
How to play against it
As White, push d4 early and develop with Nc3 and Re1. Avoid trading too many pieces, since Black's position is cramped and suffers more in a full board. As Black, do not leave the c6 knight pinned long; ...Bd7 solves it.
Questions
What are the moves of the Ruy Lopez: Berlin Defense, Improved Steinitz Defense?
The Ruy Lopez: Berlin Defense, Improved Steinitz Defense starts 1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6 4.O-O d6. Its ECO code is C66.
Is the Ruy Lopez: Berlin Defense, Improved Steinitz Defense good for Black?
Stockfish 17.1 rates the position +0.59 at depth 20, which is a slight edge for White. In 2,013 lichess games from our sample, White scored 54.3%. A safe, passive line for Black players who like solid structures; White gets an easy space edge and a long-term plan.
What is the main idea of the Ruy Lopez: Berlin Defense, Improved Steinitz Defense?
Black defends e5 with ...d6 and keeps a solid, compact position. White uses d4 and quick development to gain space and keep a lasting initiative.
What should White play next?
The engine's first choice is d4, with Nc3 and Re1 close behind. 5.d4 stakes the center and invites ...exd4, after which Nxd4 gives White active pieces.
Related lines
Updated October 2026. Sources and method.