Abdel Irada: <<•>Diagnosis by clairvoyance?<•>>Sometimes a doctor has to question, palpate, test, and question again before offering a diagnosis. On other occasions, though, he need merely look over the patient to "see" an internal pain and know what it means and how to treat it.
When this happens, it can seem uncanny, as if the doctor were using clairvoyance. Of course, the clairvoyance is really nothing more arcane than intuition: the product of intelligence guided by much experience.
Here, many players will find themselves in the role of that doctor. Looking over Black's position, they will see that the e6 square looks "tender," and so they start to palpate to confirm what they already "know": that a touch on this spot will elicit a pain reaction; for, deep inside, there is a dangerous vulnerability echoed in this little tender spot.
Sure enough:
<<•> 29. Rxe6! ... >,
and Black winces.
Of course, he can't reply (a) 29. ...Qxe6 30. Qh6, and mate cannot be avoided.
This leaves
<<•> 29. ...fxe630. Qh6 ... >
Yes, that hurts. With the pawn still on f7, this move could have been easily met by ...Qf8. But now the kingside is critically weakened; all is not well.
White threatens mate on g7. Pointless spite checks aside, Black can meet prevent this with any of four moves.
< (1) 30. ...Qf8
31. Qxg6†, Kh8
32. Qxh5†, Kg8
33. Rg1† 
>
White mates in two.
< (2) 30. ...Rb7
31. Qxg6† ... >
Which way to run?
< (2.1) 31. ...Kf8
32. Rg1 >
Black can delay mate, if he wishes, with (b) 32. ...Rg7 33. Qxg7†, Ke7 34. f7†, when White will queen with discovered check and cut away the remaining defenders.
< (2.2) 31. ...Kh8
32. f7 ... >
The threat is 33. Qh6#, and the answer is one of two:
< (2.2.1) 32. ...e5
33. Rf6, Rxf7 >
It's this or (c) 33. ...Qf8? 34. Qxh5†, Kg7 35. Qh6#.
<34. Rxd6, Rf1†
35. Kg2, Rg8
36. Qxg8† >
White has a rook and a knight to spare.
< (2.2.2) 32. ...Qf8
33. Qxh5†, Kg7
34. Rg1†, Kf6
35. Qg5†, Kxf7
36. Rf1†, Ke8
37. Rxf8† >
Farewell, option (2), which so far holds out best.
< (3) 30. ...Rd7
31. Qxg6†, Kf8 >
Black cannot play (d) 32. ...Kh8? 33. Qxh5†, Kg8 (33. ...Rh7? 34. Qe8†, Qf8 35. Qxf8#) 34. Rg1†, Kf8 35. Qh8†, Kf7 36. Rg7†, Kxf6 37. Qh6†, Kf5 38. Qg5#.
< 32. Rg1 ... >
Also playable is 32. f7, but Black can struggle on with 32. ...Rb8.
The text poses a question: I threaten 33. Qg8#. What do you propose to do about it? The answer does exist, but it's more comic than practical.
< 32. ...Rg7
33. Qxg7†, Ke8
34. f7† >
No matter where Black moves, White queens with check and wins with élan.
One try left.
< (4) 30. ...Kf7
31. Qg7†, Ke8
32. f7† >
This time, White will queen with discovered check.
Black can prolong the struggle in some of these variations, but he must finally succumb to the mortal malady that our inner chessic physician first diagnosed by the "tenderness" of e6.
∞
Kibitzing
sac: 29.Rxe6
