This week I conclude my coverage of the St Louis leg of the million dollar Grand Tour.
 
Carlsen-So: Sinquefield Cup, St Louis 2015 (see diagram 1)
 
Although Carlsen is a pawn down here his knight is so much better than Black’s bishop that this small material imbalance is essentially irrelevant. 29 a4 Bd8 30 Rd4 Kf8 31 Rfd1 Rc6 32 Ne3 Bb6 33 Nc4 Bxd4 34 Nxa5 This zwischenzug regains the pawn. 34 … Qb6 35 Nxc6 Bc5 36 Qd5 e3 37 a5 Qb5 38 Nd8 Ra7 39 Ne6+ Ke8 40 Nd4 Carlsen could have terminated the game more swiftly with 40 Nxc5 Qxc5 41 Qg8+ Kd7 42 Qxh7+ Kc6 43 Qxg6 when the pressure against d6 kills any black counterplay. 40 … Qxa5 41 Qg8+ Kd7 42 Qxh7+ Kc8 43 Qg8+ Kb7 44 c3 bxc3 45 Qb3+ Qb6 46 Qxb6+ Kxb6 47 bxc3 Bxd4 48 Rxd4 Kc6 49 Kc2 Ra2+ 50 Kd1 Rf2 51 Ke1 Kd7 52 Ra4 Ke6 53 Ra8 Rh2 54 c4 Kf7 55 Rb8 Ke6 56 Rg8 Black resigns
 
Nakamura-Grischuk: Sinquefield Cup, St Louis 2015 (see diagram 2)
 
Nakamura won an instructive endgame in the last round, gradually driving his opponent into zugzwang. 63 Bg3 h6 64 Be5+ Kh7 65 Rf7+ Kg6 66 Rf8 Kh7 67 Bf4 a5 68 Bxh6 a4 69 Be3 a3 70 Bxc5 a2 71 Bd4 Nc7 72 Ba1 Ne8 73 c5 Nc7 74 c6 Ne8 75 Kh4 Nc7 76 Kh5 Ne8 77 c7 Black resigns After 77 … Nxc7 78 Rf7+ mates quickly.
 
Carlsen-Topalov: Sinquefield Cup, St Louis 2015 (see diagram 3)
 
Here White should play 17 Nxf8 Qh3 18 Qxh3 Bxh3 19 g3 Kxf8 20 Bh6 when he is certainly not worse. Instead Carlsen overreaches and Topalov’s accurate defence quickly creates an endgame where his extra piece comfortably outweighs Carlsen’s kingside pawn mass. 17 e5 Qc6 18 f3 Qg6 19 Nf6+ Kd8 20 Qxg6 Rxg6 21 Ne4 Bb7 22 h4 Rc8 23 h5 Rg8 24 Bd2 Nc4 25 Bc3 Bh6 26 Rad1+ Ke8 27 Rd3 Bf4 28 Nf2 Bc6 29 Nh3 Bg3 30 Re2 Bb5 31 Rd1 Bc6 32 Nf2 Bxe5 33 Ng4 Bxc3 34 bxc3 Kf8 35 Kf2 Rh8 36 Ne5 Nxe5 37 Rxe5 Be8 38 g4 f6 39 Re6 Bb5 40 Rde1 Rc7 White resigns