Topalov enters this game with a difficult decision. Should he try to hold for a draw and push for an all-out win with White in the 4th game, or try to risk potentially losing the match here with Black? These are problems that the super-GM from Bulgaria must answer even before the players sit at the board.
1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.a4 Kamsky repeats his relatively experimental line from game one. Even though Topalov and his team were probably expecting this, it is very difficult to react in a mere two days. It's possible that they found no tangible improvement after 6... Nc6 7. a5!? so Topalov deviates back to the more usual Najdorf approach.
6...e5 7.Nf3 Be7 8.Bg5 Be6 9.Bxf6 Bxf6 10.Nd5 Nd7 11.Bc4 Rc8 12.b3 Qa5+ This game's novelty. This practically forces White's response, after which it would only make sense to trade queens. A superficial assessment would be to think that 'simplifications lead to draws', when in fact the absence of queens brings many new strategical ideas to the position.
13.Qd2 Qxd2+ 14.Nxd2 Bg5 This is a good time to get a strong hold of the position. The structure is very reminiscent of a Sveshnikov Sicilian. To compensate his backwards d6 pawn and weak d5 square, Black has the pair of bishops and a half open c-file. Of course, this isn't something that he can take advantage of immediately since the position is rather closed. But it contains potential! The old masters believed that obtaining the pair of bishops would eventually grant an advantage, because ultimately the position was bound to become open after pawn exchanges. Although chess has evolved greatly, this maxim still holds some value.
15.Kd1!? This is an interesting move by the American. The king is perfectly safe on d1, and it holds the queenside somewhat. There is really no advantage in sending the king to the kingside, as it would serve no purpose there. The queenside rook will eventually lift through a4 (after a pawn push to a5) and go to b4, where it would be pressuring the b7 pawn. However, White is not the only one who can push rook pawns...
15...h5! A good strategical move: Black grabs space on the kingside and prepares a potential rooklift there - but it's also important to understand the psychological implications of such a move. Because of the match situation, it is possible that Kamsky wants to play with as little risk as possible. Clearly he holds no advantage, so he does not want to commit himself to any weaknesses if he cannot see an immediate return. It is possible that for this reason he shuns the most natural move 16.h4 and gives Black a decent amount of space in the kingside. In my opinion, unnecessarily.
16.Re1?! [16.h4 is of course the most natural continuation, but then White has to cope with the fact that h4 will be weak and g5 might be a possible break in the future. All bishop retreats make some sense at this point, but the most natural would seem to be 16...Bd8 eyeing that h4 pawn. 17.g3 Ba5 Kamsky might have looked at this position and not liked it. The computer suggests that terribly inhuman move 18.Rb1, so it's understandable how he didn't go for this line. However, White's position is solid, even if rather planless.]
16...h4 Black quickly grabs the space he was provided. White can hardly allow the pawn to go all the way to h3, so he must stop it now.
17.h3 Nf6 18.Nxf6+ [18.Nb6 was a natural alternative. However after 18...Rc5 19.a5 Nh5 Black begins to build up some pressure on the kingside. Maybe saying that Black is better is not quite true, but it does seem more pleasant to play with the Black pieces.]
18...gxf6!=/+ Topalov instantly replied with this move, and with good reason. The g-file opens with great effect to pressure the now weak g2-pawn, while his center will be bolstered after the trade of bishops on e6. This move might seem strange to some players, but to a Sveshnikov player, or a super-GM like Topalov, it is the only conceivable move.
19.Bxe6 fxe6 20.Nf3 Rg8 Kamsky must hurry and prevent Topalov from expanding in the center too quickly. He still has some resources - but haste is mandatory.
21.c4 f5 22.exf5 exf5
23.Ke2! A resourceful move! The king's role in the center has ended, and there is no more need for him to defend the c2-square. Additionally, he was starting to become exposed, so it makes sense to transfer his majesty to f1, where it will guard the g2 pawn.
23...Be7 24.Kf1 Kf7 25.Rad1 This is another good moment to analyze what is going on. Black has achieved many things! He fixed his structure and now has a potentially dangerous pawn center. Unfortunately, there is no clear way for him to use it immediately. He will never want to advance e4 and give White the d4 square. So it transpires that a logical plan is to play b5. This can be done immediately, but Topalov shows his class and first plays an important move.
25...Rc5! This move takes control of the fifth rank, an important element as the 25... b5 variation shows. White is running out of useful moves, so he plays his card... [25...b5!? 26.axb5 axb5 27.Rd5! This cool moves forces off more pawns than Black wants to trade. The following is only a sample line, but shows the great simplification power White has as his disposal. 27...bxc4 28.bxc4 Kf6 29.c5! Ke6 30.cxd6 Kxd5 31.dxe7 Rge8 32.Nxh4 Ke6 33.f4 Rc5 34.g4 fxg4 35.hxg4= And with the last pawn gone the draw is obvious.]
26.b4! Maybe forced. White uses tactics to resolve some of the tension. [26.Re2 b5 27.cxb5 axb5 28.a5 b4=/+ is definitely NOT what White is looking for.]
26...Rxc4 27.Rxe5 Black has a few ways of dealing with this position. He wants to create as much play as possible, but it seems that White is holding in every line.
27...dxe5 [27...Kf6 28.Ree1 Rxb4 29.Rd4 Rxd4 30.Nxd4= And Black has no real hopes of winning as he will soon lose an important pawn.; 27...Rxb4 28.Rxf5+ Kg6 29.Ra5 The awkward placement of the rook on a5 would seem to give Black a reason to go for this line, however it is actually difficult to come up with a useful move. The pawns on d6 and h4 are rather weak, and the king will never find shelter. Practically, it is difficult to go for this line as your top choice, but it was definitely worth a try. 29...Rc8!? 30.Re1 Rc7=/+ ]
28.Nxe5+ Ke6 29.Nxc4 Bxb4 30.Rb1! Fixing the pawns on a light square is important, as it will allow White to easily control them, or at least force Black into a major concession if he tries to advance on the queenside.
30...a5 31.Rd1 Rc8 32.Rd4 The weak pawn on h4, the controlled structure on the queenside and the active white pieces give black little hope to win, so black sets up one final trap...
32...Bc3! 33.Rxh4 Bf6 34.Rf4 Bg5 White is at a small crossroads. He could try to gain three (!) passed pawns on the kingside with 35.Rxf5!? or he could play it safe and take a draw. Topalov has simply given Gata the chance to go wrong, but he doesn't bite.
35.Rd4 [35.Rxf5!? Kxf5 (35...Rxc4 36.Rxg5 Rxa4 37.Rb5+/= Black might have enough to draw this, but no more.) 36.Nd6+ Ke6 (36...Ke5? 37.Nxc8 Kd5 transposes to Kd5 above.) 37.Nxc8 So now that we reach this position in our minds, we realize that more calculation is necessary. Black has no successful way of trying to corral the knight on c8, so he must lunge toward the queenside - and he has two ways to do this. 37...b5! Speed is everything. White can't take on b5, but he can clearly catch the pawn. (37...Kd5? 38.Ke2 Now Black's king cannot prevent White's from helping on the queenside, since he cannot afford to lose the b-pawn. 38...Kc5 (38...Kc4?! 39.Nd6+ Kb3 40.Nxb7 Kxa4 41.g3 Kb4 42.Nxa5+- ) 39.Kd3 Kb4 40.Nd6 b6 41.Nb5 Kxa4 42.Kc4+- And the pawns roll by themselves on the queenside.) 38.Ke2 bxa4 39.Kd3 Bf6 40.Kc4 a3 41.Kb3 Bd4 42.Kxa3 Kd7 43.Ka4 and the position should be drawn. Of course this crazy lines requires quite a bit of calculation, and contains many ways in which one could go wrong. Gata's choice is safe and sound.]
35...Bf6 36.Rf4 Bg5 37.Rd4 Bf6 A tenacious defense by the American. Topalov tried through every flank but eventually came up short of victory, setting up a very anticipated game tomorrow, where Topalov will push with everything he has! 1/2-1/2