411 REFERENCE · Wikibooks
Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...a6/4. Ba4/4...Nf6/5. O-O/5...Nxe4/6. d4/6...exd4/7. Re1/7...d5
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Ruy Lopez:Riga Variation rd bd qd kd bd rd pd pd pd pd pd pd nd pd bl pd nd nl pl pl pl pl pl pl rl nl bl ql rl kl
Ruy Lopez:Riga Variation
8. Nxd4 keeps the threats coming while recovering a pawn (White is two pawns down, remember).
8. Bg5 aims to eliminate the f8-bishop. It allows Black to break at least one of the pins against her king, but may still be good enough for an edge. ...f6 in response can get complicated.
8. c4 tries to pressure the center and eliminate one of black's d pawns. If black chooses to take en passant with ...dxc3, white can respond Nxc3, putting another attacker on the pinned e4 knight. The response 8...Bb4 9.cxd5 Bxe1 10.Qxe1 Qxd5 11.Bb3 Qf5 is more advisable for black.
References
Nunn, John (ed.), et al. Nunn's Chess Openings Everyman Chess 1999 1-85744-221-0
Ruy Lopez