Federer vs Can

White has built the attack cleanly. 18.Qg4 and 19.h4 take over the kingside, and the rook on d1 wants to reach g3 along the third rank. Two routes lead there and only one of them earns something on the way: 21.Rd3 attacks the pawn on d5, which is covered by the e6 pawn and by nothing else.

Black cannot recapture. After 21.Rd3 Nd7 22.Rxd5 exd5 23.e6 the diagonal of the bishop on f4 is open, it looks straight at the queen on c7 and the rook on b8, and the pawn on e6 attacks the knight on d7 as well. Three attacks at once: White invests the rook for it and is clearly winning afterwards.

The move played was 21.Nd4, which puts one of his own pieces between the rook on d1 and the pawn on d5. One move later the rook did come with 22.Rd3, but without a threat, because the knight is standing in the way. The difference is not quite a pawn. The rule to take home: when a piece can reach its square by two routes, take the route that attacks something on the way, and never block the file your own rook is about to work on.

White has everything in place: queen on g4, rook on g3, pawn on h5, black king on h8. The move that turns it into something is 24.h6, and it has to come at once. After 24.h6 g6 the g7 pawn has to move, the white pawn stays on h6 as a wedge, and the dark squares f6 and g7 belong to White for good. Those squares are exactly what the bishop on f4 is there for.

The move played was 24.Bg5, offering a trade of dark-squared bishops. That removes the very piece that was supposed to occupy those squares. After 24...Bxg5 25.Qxg5 h6 Black chases the queen away with tempo, the attack is over, and the position is completely level. Three quarters of a pawn gone in one move.

In an attack you trade the defenders, not the attackers. Before you offer an exchange, work out which of your pieces comes closest to the enemy king, and then ask whether that is the one about to leave the board.

The position had long been level again, and White had given up the f4 pawn on purpose: 30.Rg6 was the best move on the board and 31.Rf1 after it as well. Then Black put the queen on the other side of the board with 31...Qd2, far away from his own king, and White is suddenly just under two pawns better.

32.Nxe6 is the move: knight and rook both aim at g7. After 32.Nxe6 Rg8 the black rook is tied to the defence, and the white rook stays on g6 where it does the work. Most players take with the knight here, because the knight is the smaller of the two pieces in this attack.

The move played was 32.Rxe6, and the whole difference is which piece captures. After 32...Rxe6 33.Nxe6 the rook that stood on g6 is off the board, and the attack goes with it. The question behind it is a small one and it decides whole games: when two pieces can take on the same square, take with the one whose job is done.

One move earlier White had answered the same question correctly. After 36...Qe3+ there were three legal moves and only 37.Kh2 holds: 37.Kh1 Ng3+ 38.Kh2 Nxf1+ wins the rook for Black. Now, on move 38, two moves are left, and 38.Kg1 draws. After 38.Kg1 Qe3+ 39.Kh2 Qg3+ 40.Kg1 the position repeats, and Black has nothing better.

38.Kh1 looks like the same thing and loses, because from h1 the knight comes to f2 with check. After 38.Kh1 Nf2+ 39.Kg1 Ng4 Black threatens mate on h2: the knight on g4 covers f2 and h2, and White’s own rook on f1 takes the last flight square away from the king. The only answer left is to give up the queen with 40.Qxg4.

The game went 40.Nf8+ Rxf8 41.Rxf8 Qe3+ 42.Kh1 Qe1+ 43.Rf1 Qxf1, and White resigned on the check. Colin Federer had a little over two minutes on the clock at that point and three moves to go to the time control, and he played 38.Kh1 within seconds. Two legal moves are not a relief, they are an invitation to calculate both: the difference between g1 and h1 is one square and the question of whether the knight reaches f2 with check.