Do not neglect King Safety

This lesson is from a Friendly Game,  Donidon (1813) - Lemma (2007).  I am ahead a pawn as Black, but my King's pawn structure is a bit loose.   Donidon (of South Africa) has the long term worry of not only the lost material but the isolated a and c pawns, but Black has no immediate threats of consequence.  (In fact, Black has to deal with his cumbersome back rank Rook and Bishop pair babysitting the b pawn.) White meanwhile is poking at Black's Kingside pawn structure, and Black's job is to suppress counterplay and preserve King safety.  Donidon has just played 32.Rh3-h5 and I underestimate the threat.  It is time to play cautiously and solidify the pawns around my King with 32...f6, but I play the excessively aggressive 32...f5 instead.

Donidon follows immediately with a rook sacrifice intent on blasting open my Kingside: 33.Rxg5+ hxg5 34.Qxg5+ and I face the prospect of repeated check draw -- or worse!  34...Kf7 35.Qh5+ Kg8 36.Qg6+ Kf8 37.Qf6+ Ke8 and I am thinking it is time to accept the draw.  But then Donidon plays 38.Rd1 ... and I realize he is actually hoping for the full point!  So having gone from up a pawn to up a rook, I am now fighting for a half-point against a lower rated opponent -- all because I didn't fortify with f6 and got impatient with the overextended f5 on my 32nd move. 

This position is after white's declarative 38. Rd1 at which time I learned he was fighting for a win.  I had to bear down and not make any more mistakes  Most notably, I must prevent Rd8++ : 38...Qe7 (if he allows the trade of Queens, of course I win -- I am up the sacrificed rook.  So White's job is to keep up the checks or maneuver me into a mating net or the loss of my Queen.) 39. Qh8+ Kf7 40.Qh7+ Kf6 41.Qh4+ Kf7 42.Qh7+ Kf6 43.Qh4+ Kf7 (at this point he should be offering a draw, as there is no headway to be made) 44.Qh7+ Kf6 1/2 -1/2

The half point thrown away carelessly because I failed to suppress counterplay and ensure my King's safety.

If you return to the first diagram, you will see that ...f6 has an additional quality -- when the pawn is not on the 5th rank it is not blocking the Black Queen from defending against a more persistent onslaught on the g pawn.  For example, after 32...f6 if White persists with his sacrifice theme and plays 33.h5 Black has at his disposal 33...Bd7 34.hxg5 fxg5 and now 35.Rxg5+ can be met by either the relatively safe 35...Qxg5 despite 36.Qb2+ or, for the more daring, 35...hxg5 36.Qa1+ Rd4 and Black has a bit more work to do regrouping, but his game is won. 

One more note: Fritz 8, even at a depth of 14 ply, recommends the mistaken ...f5.  Chess engines fail to appreciate positional subtleties such as this one. Rybka 2.3.2 does not reject ...f5 in favor of ...b5 and then finally finds... f6  until 14 ply!  So the right positional move in this position takes even a very good engine 14 ply to find -- human minds still have something to say about chess strategy!