Surely Alexei Shirov isn’t counting on queening his pawn? No, of course not. By advancing to d7, the pawn cuts the black position into two halves, and is also prepared to lay down its life in due course. The other important thing is that he opens a group of squares for the attack – d5 for the knight, d6 for the white queen, and also the a2-g8 diagonal.

The knight heads for d4, but this does not bring great benefits, since the other black pieces are uncoordinated, especially his rooks.
It was stronger to open up the bishop with 14...e4, or stop the white pawn by 14...Nd7.

Thanks to the knights, a mating net is forming around the black king.

Black has no moves to strengthen his position, so White permits himself some prophylaxis – the king moves away from the knight check.

Black resigned.

Black threatens perpetual check, so White must seek a way to advance his pawn with tempo.

Promoting to a queen is no good, so we promote to a knight! The white forces are sufficient to cope with the lone black queen.

Both sides’ passed pawns are very far advanced, and each is a potential queen. Therefore, to gain a tempo, Black sacrifices a rook:

The armada of black pawns marches unstoppably to the promotion squares.