When I saw this combination on the homepage I thought "easy! Qf3 threatens mate, but after the forced Qd7 then comes Nxc5 this allows the queen to invade." Working with this idea, the line I came up with was 11. Qf3 Qd7 12. Nxc5 Qxc5 13. Qf7+ Kd8 14. Qxe5?? which I thought was a clever way to snatch a pawn (...Bxd6 15. Nxd6+ wins the queen back)

One little wrinkle. After 14. Qxe5?? Black simply plays ...Qxc2 and the White queen is trapped! (15. Qf7 Bd4+ 16. Kf1 Qd1#)

Tal, however, knew that "only fools rush in." First, the attacker must provoke weaknesses to justify the attack. Qh5!+ is just the ticket, as this can only be met with g6, which weakens the f6 square.

And so the REAL answer to this problem is: 11. Qh5+! g6 12. Qf3 Qd7 13. Nxc5 Qxc5 14. Qf7+ Kd8 15. Qf6+ snatching the rook.

Notice that this combination really began with 10. Bxc6, for if 10. Qh5+ g6 11. Qf3 Black simply plays Nxe5. So to answer the age-old question of how many moves a GM sees ahead, I would say "at least five."