Jan1908   Shajmaty: 19. ♗d4? lets Black escape. 19. ♕h5 looks better to me... 

Jan2711   Jim Bartle: Shirov thinks 22 c4 was white's first weak move, recommending 22 Rd2. 

Sep2416   dfcx: black is down an exchange with 2N + P against R+B. In addition the knight is en prise, while the white bishop is safe (27...gxf6? 28.gxf6+ Kf8 29.Rg1) My idea for black to get out of the hole is:
27...c2 28.Rd2 Nd4
Now black can bring up the second knight with Na5, and white's bishop still lacks escapes. White can save the bishop by exchanging rook for knight. 29.Rxd4 exd4 30.Bxd4 Qa5 to guard against Rc3
aiming for Qe1+, while threatening Qxg5 if the rook moves away. White is hopeless. click for larger view 

Sep2416   yadasampati: I could see too that it was c2 

Sep2416   YouRang: I guessed 27...c2, with the idea of ...Nc3, but I missed ...Qa5! which makes the idea work. 

Sep2416   patzer2: Back on track with my Saturday solution 27...c2! . Got five out of six correct this week, missing only the complex stalemate combination in yesterday's Friday puzzle.. My winning followup was different than the game continuation. After 28. Rdd3, I went for 28...Nd4 which wins after 29. Rxd4 exd4 30. Bxd4 Qa5 31. Bc3 Rxc3 32. Rxc3 Qxc3 33. Qxc2 Qe1+ 34. Kb2 Nc5 (4.12 @ 20 depth, Deep Fritz 15). Of course after 28. Rdd3 the strongest followup is the game continuation 28...Qa5 (10.41 @ 20 depth, Deep Fritz 15). The computer indicates White's decisive mistake was the passive 27. Qa2?, allowing 27...c2 . Instead, 27. Qc4 Qd7 28. Qb4 Na7 (0.97 @ 20 depth, Deep Fritz 15) makes a fight of it. Earlier, instead of 24. Bf6, allowing 24...Qc7 , Black might have fared better with the simpler 24...Nxc8 =. Play after 24...Nxc8 might go 25. Qc2 Nc5 26. a4 Na3 27. Qa2 Nxe4 28. Qxa3 Nxg3 29. hxg3 c2 30. Rd2 Qb7 31. Rxc2 Rxc2+ 32. Kxc2
Qe4+ 33. Kc3 Qe1+ 34. Kd3 Qd1+ 35. Ke3 Qe1+ 36. Kd3 Qd1+ 37. Ke3 Qe1+ 38. Kd3 = with a draw by perpetual. 

Sep2416   patzer2: The computers like <Shajmaty>'s 2008 suggested improvement 19. Qh5 (0.38 @ 23 depth, Stockfish 7). Also good is 19. Rh3 (0.34 @ 22 depth, Deep Fritz 15). 

Sep2416   AlicesKnight: Nicely done (saw some of the individual moves but could not combine them). 

Sep2416   gofer: Okay, so black is a pawn up, but an exchange down, so pretty equal. Black has a nice
advanced pawn on c3. But the only important thing about this position is the state of
Bf6... ...oh what was white thinking...?! So our long term objective is swap off
everything and move into a won end game where we are a knight up. But first we need
to find a way to win back the exchange, so that white has no chance to end up with a
rook in this "winning" end game, because that might make our life difficult. <27 ... c2>
This puts black to an immediate decision. Rd1 must move, but needs to avoid knightfork
squares, like g1 and d5. But, the whole point of c2 is not really to attack Rd1, but to
free up c3 as a square for our knight!
28 Rd5/Rd4/Rf1/Rg1/Rh1 Nc3
29 Qb2/Qa1/Qxc2 Ne2+
28 Rd3 Qa5!
Black threatens Qe1+ mating and can no longer play axb5 due to Qxa2 mating! 29 Rg1 Nc3
30 Rxc3 Qxc3 (Qb2/Qa1/Qxc2 Ne2+ )
White is in real trouble, black has already one back the exchange and is looking to win Bf6, but if the bishop moves black plays Na5/Nc5 winning, so white must let Bf6 die and play b4, white is forlornly hoping for something like Qxf7+ working, but really this is not going to happen... 31 b4 Qxb4
Now white's position is in tatters Na4/Nc5 is coming and it is unstoppable... <28 Rd2 Nc3>
29 Rxc2 Nxa2+ mating
29 Rxc3 Qxc3 The rook must move due to Qxd2+ Kxd2 c1=Q+ winning 30 Rxc2 Qe1+ (Re2 gxf6 )
31 Kb2 Rxc2+
32 Kxc2 Qxf2+!
33 Kb1 Qxg3! (Kc1 Qxa2 or Kd3 Nc5+ 34 Kc4 Qd4#) 34 hxg3 Nf3+
<29 Qxc2 Nxe4>
click for larger viewBlack achieved what it aimed to in the first place, the exchange is going to happen
and the queens are going to be traded off. At that point Bf6 is dead and so is white. ~~~
Doh! I found <28 ... Qa5!>, but missed the only defence <29 Rge3> which makes things far more interesting. But as I wanted to play Nc5 anyway in
most scenarios I might have found the main line had I got that far... ...half a point at least...
:) 

Sep2416   gofer: Ahh!, just realised that I got more than a little confused in one
of the lines...
27 ... c2
28 Rd2 Nc3
29 Rxc3 Qxc3
30 Rxc2 Qe1+ (Re2 gxf6)
31 Kb2 Rxc2+
32 Kxc2 Qxf2+!
33 Kb1 ...
click for larger viewSome how I thought Rg3 was still on the board and so was Nb5 and
wrote the following drivel...
33 ... Qxg3! (Kc1 Qxa2 or Kd3 Nc5+ 34 Kc4 Qd4#) 34 hxg3 Nc3+
I think the following would be okay too...
33 Qg1+ Kb2
34 Qxh2+ Ka3
35 Qxa2+ Kxa2
36 gxf6 h5
click for larger view 

Sep2416   scholes: Rd3 is just a blunder. I had c2 Rd2 Nd4 and guess what SF says Nd4 better than Nc3 which was initially its first choice. The point is black is going to play Qa5 in all lines game continuation or Nc3 or Nd5 and will win a piece 

Sep2416
  OhioChessFan: c2 seemed obvious, and I think I was pretty lucky to get the rest of the puzzle after that. A bit too tactical for me, but I got lucky and the first move I tried tended to work out. Instructive is why 28. Rd2 doesn't work for White. 

Sep2416   RandomVisitor: After 27...c2
click for larger viewKomodo10.164bit:
<5.25/37 28.Rd2 Nc3 29.Qxc2> Qa5 30.Kb2 Nxa4+ 31.bxa4 Rxc2+ 32.Rxc2 Nc5 33.Be7 Qc7 34.Rb3 h6 35.g6 fxg6 36.Bh4 Qa7 37.Re3 Nxe4 38.Bg3 Qd4+ 39.Kb1 Nc5 40.Rec3 Qb4+ 41.Ka2 Qxa4+ 42.Kb2 Qb5+ 43.Ka1 Nb3+ 44.Ka2 Qa4+ 45.Kb2 Nd4 46.Rc8+ Kh7 47.R2c3 Qb5+ 48.Ka2 g5 49.h3 Qe2+ 50.Ka1 Qe1+ 51.Kb2 Qd2+ 52.Kb1 a5 53.Re3 a4 54.Ra3 Kg6 55.Rac3 Nb5 56.R3c6 Qd4 12.51/37 28.Qb2 cxd1Q+ 29.Kxd1 Nc3+ 30.Ke1 Nxe4 31.Re3 Nc3 32.g6 hxg6 33.Bg5 f6 34.Bxf6 gxf6 35.Qc2 f5 36.h4 Qc6 37.Rh3 Nd5 38.Qxc6 Rxc6 39.Rg3 Kf7 40.h5 gxh5 41.Rg5 Nf4 42.Rxf5+ Ke6 43.Rf8 Nc5 44.Rb8 Ne4 45.Kd1 Nxf2+ 46.Kd2 Ne4+ 47.Kd1 h4 48.b4 Nc3+ 49.Ke1 Nxa4 50.Kf2 h3 51.Kg3 Rc3+ 52.Kh2 Rc2+ 53.Kh1 Nc3 54.Rc8 Kd5 55.Rc7 e4 56.Re7 Rb2 

Sep2416   Patriot: 27...c2 28.Rd2 Nc3
29.Qxc2 Nxe4 30.Qxc7 Rxc7+ 31.Rc2 Rxc2+ 32.Kxc2 Nxg4 29.Qb2 Nxe4 30.Rxc2 Qxc2+ 31.Qxc2 Rxc2+ as above . 

Sep2416   Patriot: I forgot to include,
29.Rxc3 Qxc3 30.Rxc2 Qe1+ 31.Kb2 Rxc2+ 32.Kxc2 Qxf2+ 33.Kb1 Qxa2+ 34.Kxa2 gxf6 

Sep2416
  catlover: Didn't get it, but sure enjoyed seeing the solution played out. 

Sep2416
  agb2002: Black has two knights and a pawn for a rook and a bishop. White threatens axb5.
The first idea that comes to mind is 27... c2. Other options are 27... Nd4 directly and 27... gxf6. In the case of 27... c2:
A) 28.Rdg1 Nc3
A.1) 29.Qxc2 Ne2+ wins.
A.2) 29.Qb2 Ne2+ 30.Kd2 Nxg3 31.hxg3 c1=Q+ 32.Rxc1 Qxc1+ 33.Qxc1 Rxc1 34.Kxc1 gxf6 35.gxf6 Nc5  + [N]. A.3) 29.Rxc3 Qxc3 with double threat Na5 and gxf6 looks winning. B) 28.Re1 Qa5 (28... Nc3 29.Qa3)
B.1) 29.Ree3 Qd2+ 30.Kxd2 (30.Kb2 c1=Q#) 30... c1=Q+ B.1.a) 31.Ke2 Nd4+ 32.Kd3 Nc5# (or Q(R)c3#).
B.1.b) 31.Kd3 Rc3+ 32.Ke2 Nd4#.
B.2) 29.Rge3 Nc3 (29... gxf6 is probably enough to win) B.2.a) 29.Qa1 Qb4
B.2.a.i) 30.Kxc2 Nd5+ followed by Nxe3 wins decisive material (31.Kd3 Nf4#). B.2.a.ii) 30.Rg1 Nxe4 31.Re2 Na5 looks crushing. B.2.b) 29.Qb2 Nd1 wins decisive material.
B.2.c) 29.Qa3 gxf6 30.gxf6 Nb1 31.b4 (due to Qd2+ and Nxa3) 31... Qd8 followed by Qxf6 looks winning. For example, 32.Rg3+ Kf8 33.Reg1 Qxf6 34.Rg8+ Ke7 35.Qg3 (35.Rxc8 Nxa3) 35... Nc3 with the double threat Ne2+ and Na2+ (36.Kb2 Nd1+ wins decisive material). B.2.d) 29.Rxc3 Qxc3 30.Re2 (30.Re3 Qd2+ wins) 30... Na5 followed by Nxb3 wins. C) 28.Rd2 Nc3
C.1) 28.Qxc2 Nxe4 wins decisive material. For example, 28.Qxc7 Rxc7+ 29.Rc2 Rxc2+ 30.Kxc2 Nxg3 31.hxg3 gxf6  + [N]. C.2) 28.Rxc2 Nxa2+ wins.
D) 28.Rd5 Nc3 29.Qb2 Nxd5 30.exd5 gxf6 wins a piece. 

Sep2416   mel gibson: I saw the first move in under 5 seconds but not all the rest. 

Sep2416
  steinitzfan: So can Black have his cake and eat it too? Once his knight is safe can he take the bishop on move 29 and still roll up the queenside? I don't have access to the silicon monster this weekend. 

Sep2616
  steinitzfan: No. Faced with my capture, Fritz lowered the evaluation from app. 12 to 2. He immediately fired off 30b4 which won back a knight  although with a material deficit. I honestly thought Black could wait a move and his attack would retain its strength. 
