this capture is the start of the Open Variation. This variation of the Ruy Lopez received attentions as a result of the World Championship matches between Karpov and Kortchnoi. Black chooses dynamic counterplay over solid defences: he makes spaces for his pieces to develop onto active posts at the cost of having to make some concessions with his pawn structures.
6.d4 b5 7.Bb3 d5 8.dxe5 Be6 9.Nbd2 is the move that Karpov popularized and the first major crossroads in the opening. The main idea is to put pressure on Black's strong knight on e4. This pressure is usually enhanced with moves like c3 and Bc2. So Black is asked on what to do with this N. [9.c3 and the Dilworth Variation are examined later in the game Elburg,J - Kane,K]
9...Nc5 one of White's plans in this position is to play Re1 and the usual N manoeuvre Nf1-g3/e3. White's pieces would then be ready for an attack on the black kingside with the help of the e5 pawn. White can also play Nb3, challenging the Nc5 in order to put the White Q in d3 and attack (with Bc2) the h7 pawn. On the other hand, Black often delays castling in order to improve the position of his pieces. [another chance is 9...f5 ]
10.c3 d4 a critical move, even if Black has many other choices.
11.Ng5 the move is an invention of Karpov's trainer Igor Zaitzev and was first played in the game match #10 Karpov-Kortchnoi, Baguio 1978.
11...dxc3 12.Nxe6 fxe6 13.bxc3 Qd3 [13...Nxb3 14.axb3 Qd3-> 15.Qh5+ g6 16.Qg4 Qf5 17.Qe2 Nxe5 18.Ne4 Bg7 19.Ba3 0-0-0 20.Be7 Rd7 21.Rxa6! ]
14.Bc2! this move is the prelude of a rook sacrifice [the game Karpov-Kortchnoi continued 14.Nf3 Qxd1 15.Bxd1 (15.Rxd1 Nxb3 16.axb3 h6= ) 15...Be7 16.Be3 Nd3 17.Bb3 Kf7 18.Rad1 Ndxe5 19.Nxe5+? (19.Ng5+ Bxg5 20.Bxg5!! ) 19...Nxe5 20.Bf4 Nc4 21.Bxc4 bxc4 and Kortchnoi managed to draw.]
14...Qxc3 15.Nb3 Black can decline the Rook with
15...Rd8 but [15...Nxb3 16.Bxb3 Nd4 17.Qg4 Qxa1 18.Bxe6 Rd8 (18...Qc3! 19.Bd7+ Kf7 20.Be3 Bc5 unclear ) 19.Bh6 Qc3 20.Bxg7 Qd3 21.Bxh8 Qg6 22.Bf6 Be7 23.Bxe7 Qxg4 24.Bxg4 Kxe7 25.Rc1 and the endgame is winning for White. Kasparov-Anand, New York PCA, Wch (10) 1995]
16.Bd2 Qxe5 [16...Rxd2 17.Nxd2 Nxe5 (17...Qxe5 18.Re1 Qf6 19.Nb3 ) 18.Nb3! White advantage in Khalifman-Hracek, Parnu 1996]
17.Re1! with initiative Qd5 18.Qg4 Ne5 19.Rxe5 Qxe5 20.Re1 and White is winning. I haven't found any game with the 14.Bc2 line besides those from Kasparov and Khalifman probably because nobody would like to investigate these complications even if it seems that Black's most resilient defence is 18...Qc3 where according to GM Emms White has many promising continuations but there isn't a clear win. Of course Black has other moves besides 11...dxc3, like 11...Bd5 or 11...Qxg5 but is there anything else after 11...dxc3? We will try to anwser in the next game.