C66: Ruy Lopez, Berlin defence, 4.O-O, d6

C66 Sub-variants:

• Ruy Lopez, Berlin defence, 4.O-O, d6
  1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O d6
• Ruy Lopez, Berlin defence, hedgehog variation
  1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O d6 5. d4 Bd7 6. Nc3 Be7
• Ruy Lopez, Berlin defence, Tarrasch trap
  1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O d6 5. d4 Bd7 6. Nc3 Be7 7. Re1 O-O
• Ruy Lopez, closed Berlin defence, Bernstein variation
  1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O d6 5. d4 Bd7 6. Nc3 Be7 7. Bg5
• Ruy Lopez, closed Berlin defence, Showalter variation
  1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O d6 5. d4 Bd7 6. Nc3 Be7 7. Bxc6
• Ruy Lopez, closed Berlin defence, Wolf variation
  1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O d6 5. d4 Bd7 6. Nc3 exd4
• Ruy Lopez, closed Berlin defence, Chigorin variation
  1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O d6 5. d4 Nd7