The rule of thumb for weighing up piece exchanges says that pawns are worth one, knights and bishops three, rooks five and queens nine. It is such a useful guideline that one can go a long way without ever questioning it, but strong players have a feeling for the limitations.
The first diagram shows a critical moment from the final of the New in Chess Classic, the latest online event in the Meltwater Champions Chess Tour, which was won by Magnus Carlsen. He didn’t hesitate to sacrifice rook for knight and pawn, because the resulting position looks so cosy for Black. The knights on f6 and h5 are secure and ready to jump into e4 and g3. White’s pawn on f5 is an impediment to his own pieces, so the bishop and rooks are bystanders, while the pawn on e3 is permanently weak.
Carlsen’s judgment has been honed by his peerless knowledge of historical examples. Tigran Petrosian, the world champion most famed for his positional exchange sacrifices (rook for bishop or knight) played a comparable idea against Vlastimil Hort in 1970, shown in the second diagram. By playing 21…g6, Petrosian invited the knight check on f6, and after the exchange of pieces White’s attack ground to a halt. Black’s pawns and knights formed a cohesive unit, and the White pieces were reduced to aimless shuffling. In the final position, the advanced pawn on d3 could not be prevented from queening.
Perhaps it is not a coincidence that Carlsen’s first tournament victory in the Champions’ Chess Tour came just days after his world championship challenger was decided in Yekaterinburg.
Hikaru Nakamura–Magnus Carlsen
New in Chess Classic, May 2021
24…Rxe5! 25 dxe5 Qxe5 26 Qc3 Qg3 27 Qe1 Qd6 28 Qf2 Re8 29 Rcd1 Qe5 30 Rd4 c5 31 Rd2 Ng3 32 Rfd1 Kf8 An important subtlety. 32…Nge4 would be premature, as after 33 Bxe4 Nxe4 34 Rxd5 Nxf2 35 Rxe5 Rxe5 36 Kxf2 Rxf5+ 37 Kg3 White has every chance of drawing the rook endgame. 33 Rd3 Nfe4 34 Qe1 Qf6 35 Rxd5 Qxh4 36 Bxe4 Qh1+ 37 Kf2 Nxe4+ 38 Ke2 Qxg2+ 39 Kd3 Black has a choice of winning moves, perhaps the simplest being 39…b5 to prepare c5-c4+ and Qg2xb2+. White resigns
Vlastimil Hort–Tigran Petrosian
21…g6! 22 Nf6+ Rxf6 23 exf6 Nf7 24 Qd2 Rxd4 25 Rd3 Rh4 26 Rh3 Rg4 27 Kf1 Nd6 28 Re1 Kf7 29 Bc3 Ne4 30 Qd3 Nc5 Black need not rush to capture the pawn on f6. Later it will be captured under more favourable circumstances. 31 Qd1 Rc4 32 Bb2 b5 33 Qe2 Qd6 34 Kg1 Ne4 35 Rd3 Qc5 36 Rc1 e5 37 Qe3 d4 38 Qe2 Nxf6 39 Rdd1 Nd5 40 Qd2 e4 41 Qg5 Nc7 42 Rd2 Ne6 43 Qh4 a5 44 Rcd1 Rxc2 45 Rxc2 Qxc2 46 Rc1 Qxb2 47 Rxc6 d3 48 Ra6 Qd4 White resigns