4...Nf6 (Main Line Ruy Lopez)
- By seeing White last move (4.Ba4), Black assume that White didn't want to exchange Bishop with Knight immediately.
- So, Black delayed b5 move and try to attack undefended White Pawn on e4 with his/her Knight.
- By playing 4...Nf6, Black also developing g1 Knight into best starting development square.
- By playing 4...Nf6, Black moving piece which required to be moved, in order to castle on the kingside.
- This position can be reached by 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6.
White Responses
5.O-O (C78: Ruy Lopez, 5.O-O)
- Black last move, threaten to capture unprotected White Pawn on e4.
- White can protect White Pawn on e4 directly (by playing 5.d3 5.Nc3 or 5.Qe2) or indirectly by playing this move (5.O-O).
- By playing 5.O-O, White try discourage Black to capture White Pawn on e4 (Black can capture the pawn, but White easily regain material balance).
- Because If Black play 5...Nxe4, then With play 6.Re1 followed by Rxe5 or Nxe5 on later move easily regain material balance.
- The result of this line, open the center and make Black position little unsecure (Black King still in center).
- But, if Black player like open position 5...Nxe4 playable to response 5.O-O.
- By playing 5.O-O, White also secure his/her king into safe position and bring rook into active position.
5.d3 (C77: Ruy Lopez, Anderssen Variation)
- White directly protecting pawn on e4 by using d pawn.
- Although this move seem passive, but there is hidden threat.
- Black must realize, because e4 has been protected, therefore Black cannot easily regain material balance if White play Bxc6 and Nxe4.
- There are two methods to nullify the threat.
- First, Black must immediately block White Bishop to capture Black Knight on c6 by playing b5.
- Second, Black can protect e5 pawn from White Knight attack using d pawn by playing d5.
- Protecting Black Pawn on e5 using Bishop or Queen is inferior move.
5.Nc3 (C77: Ruy Lopez, Four Knight Variation)
- White try different method to protect e4 pawn.
- Instead using d pawn to protect e pawn like in Anderssen Variation.
- In Four Knight Variation, White using Knight to protect e pawn.
- This move has draw back, because it block White to play c3 and d4 to open the center (Ruy Lopez Standard Plan).
5.Qe2 (C77: Ruy Lopez, Wormald Attack)
- Instead using d pawn or Knight, In Wormald Attack White using Queen to protect pawn on e4.
- By playing this move, White still have chance to play c3 and d4 to open the center.
- The draw back of this move is the position little unsecure for White (because e file is likely to get opened, and White Queen may become target of attack).
5.d4 (C77: Ruy Lopez, Mackenzie Variation)
- White using different approach to fight Black threat of capturing pawn on e4.
- White plan on playing d4 is to deflect Black Knight in order to leave c6 square by advancing d pawn to d5 on later move after playing 5.d4.
- Deflection is chess tactic which force opponent piece to leave certain square, in order to make that piece leave specific duty which have been assigned.
- In this position, Black Knight assigned to protect Black Pawn on e5.
- White using deflection to make Black Knight leave c6 square.
- If Black playing 5...Nxe4 then white play 6.d4 to deflect Black Knight.
- Black retreat to e7 by playing 6...Ne7 is favorable for White.
- But if Black play another move, then it is another story.
- The draw back of this move is Black has good response to 6.d5.
- By playing 6...Nc5, Black Knight trapping White Bishop with no retreat square.
- The result position is slight better for Black.
- Ruy Lopez Mackenzie Variation is good for unprepared opponent or surprise weapon.
5.Bxc6 (C77: Ruy Lopez Bayreuth Variation).
- This move is like Ruy Lopez Exchange Variation which White capture Black Knight on c6.
- The difference is White delayed playing Bxc6 (therefore this move also called Exchange Variation Deferred).
- In standard exchange variation, White play Bxc6 on fourth move.
- In delayed (deferred) variation, White play Bxc6 on Fifth move.
