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May-20-16
 | | Penguincw: Not sure if the knight sac was obvious, but I didn't even get the first move. I was hoping to pin the knight to the king and then play Bf5, but Nac8 saves the day. |
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May-20-16
 | | An Englishman: Good Evening: More a test of intuition than tactics. Impossible to analyze every variation over the board, so you have to trust that those two mighty central passed pawns will crush the disjointed Black pieces. |
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| May-20-16 | | agb2002: White has the bishop pair for a bishop and a knight. Black threatens 31... Rxg5.
The first idea that comes to mind is 31.Rb8, trying to exploit the poor position of the black pieces but 31... Nac8 or 31... Nec8 seem to hold. Another option is to attack Black's pawn chain with 31.Nxc5 dxc5 32.Bxe5. For example, 32... Rxg5 33.Bxf4 Rh5 34.Be3 followed by Bxc5 gets three passed linked pawns for the piece. I'm not sure but I think I'd play 31.Nxc5. |
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| May-20-16 | | Once: I think this is an instance where you need to turn off your targeting computer and "use the force, Luke". Two protected central passed pawns in return for a knight? That sounds like a good wager. |
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| May-20-16 | | diagonalley: well, clearly 31.NxP gives white powerful, connected passed pawns in exchange - but there's still a long way to go - way too far to calculate to a degree of certainty... so it has to be a leap of faith - albeit justified IMO. |
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| May-20-16 | | AlicesKnight: Trying to blow a way through with Nxc5 or Bxe5 looks possible, getting 2 Ps for a piece and combining with Rb7 somewhere, but I don't see a quickly decisive line. Let's see - OK, he used the N, and I didn't see the switch of the R to the K side which was lethal (33.... Rh5 possible?). |
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| May-20-16 | | Geronimo: There are instinctual elements to this one, but there are also principal considerations of positional play that can push you in the right direction. There are no immediate threats against the white king or pieces, and black's pieces are scattered and uncoordinated. White has grabbed the centre, has more mobility, his king is safer, and he simply controls more territory. Most importantly, blacks pawn at d6 is overburdened, rendering the whole pawn chain vulnerable. Nxc5 just screams out: Variations and calculations be damned, it's full speed ahead. |
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| May-20-16 | | gofer: The knight sacrifice seems to be the easiest way to get a large advantage, apart from winning three pawns
it also releases our LSB.
<31 Nxc5 ...>
31 ... Rxg5
32 Ne6 ...
32 ... Rg2/Rg3/Rg4
33 Rh1 winning the rook due to the threat of 34 Rh8+ mating! 32 ... Rh5
33 Ng7+ Kf7
34 Nxh5 
White has gained a pawn and an exchange, so black must accept the knight sacrifice. <31 ... dxc5>
<32 Bxe5 Rxg5>
<33 Bxf4 Rh5>
<34 Be3 ...>
click for larger viewThe knight sacrifice isn't just for two pawns, it is for three. Pc5 cannot be defended. After that Pa6 will be difficult to defend too. Alternatively white can advance Pe4 and then at some point play Bxg6+! The other point being how Na7, Bd8 and Ne7 are all really badly positioned at this point in time. Not only are they blocking each other but they are also restricting the king's choices too... ~~~
I don't see this as a simple defence for black.
I wonder what our silicon friends are saying about the best continuation for black? Is it <33 ... Rh5> or <33 ... Rg4>. As others have said Nxc5 seems to be a <leap of faith>, but <Once> you see that Pc5 is on offer too, then the trade of a knight for 3 connected-central-passed pawns is surely a "no-brainer"... ...that white chose to ignore taking Pc5 completely, shows just how strong he felt his position is! |
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| May-20-16 | | Eduardo Leon: Another nice minor piece sacrifice to destroy a pawn fortress: Spassky vs J Penrose, 1969 |
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May-20-16
 | | scormus: Good puzzle, and excellent comments. 31 Nxc5 looked the obvious move for a puzzle, but would I have played it in a game with anything at stake? The scenario, I play something else, Rb7 say. My team mate asks,"why didnt you play Nxc5? It wins" "How do you know?" "Of course it wins, these positions always do" |
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| May-20-16 | | Eduardo Leon: White's nicest move in this whole sequence was 35.♖h1!, winning a crucial tempo by threatening to win the rook outright with 36.♔f3. I don't understand why black played 34...♘ac8, though. Not that I can find anything better. |
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| May-20-16 | | cocker: It may be instructive to note that the alternative sacrifice 31 Bxe5, is not as good. |
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| May-20-16 | | Underworld: At first I tried looking for pins, but then it became obvious that the knight sac on c5 would allow the dark squared bishop to eat up blacks pawns (3 pawns for a knight is equal) and negate black's threat with the g-pawn. The strong center, bishop pair, and rook on the 7th rank would allow white to apply an ample amount of pressure with a winning position. I didn't see all the moves, but Nxc5, Bxe5, Bxf4 were very obvious. |
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| May-20-16 | | patzer2: For today's Friday puzzle, my instinct is to play 31. Nxc5 as in the game. That's because giving up the Knight for two central passed appears to be a winning plan. However, Fritz and Stockfish indicate White can strengthen the Nxc5 plan by first preparing it with 31. Rb7! The Stockfish program (24081364) at 29 depth on SCID vs PC gives its top two moves as 31. Rb7! (+2.42) and 31. Nxc5 (+1.87). Stockfish and Fritz both give best play after 31. Rb7! as 31...Nac8 32. Nxc5 dxc5 33. Bxe5 Rxg5 34. Bxf4 Rg4 (diagram below) 
click for larger viewwhen White has the pleasant choice between the two winning lines 35. Kf3 Rxf4+ 36. Kxf4 (+2.58 @ 26 depth,Stockfish 24081364) or 35. Bg3 Ba5 36. Kf3 Rg5 37. Bf4 (+2.78 @ 26 depth, Stockfish 24081364). |
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| May-20-16 | | patzer2: Lest anyone suggest Suttles' "modern" opening strategy 1. c4 g6 is out of date and unplayable, they should take a look at the recent computer game
Protector vs Komodo, 2016 when Black was able to equalize and draw after 4...Nc6. |
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| May-20-16 | | morfishine: <cocker: It may be instructive to note that the alternative sacrifice 31 Bxe5, is not as good> Good point, both need to be looked at |
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May-20-16
| | scormus: <patzer2 31 Rb7! Nac8 32 Bxc5> I just did the same as you and got the same result with Rybka. I suppose it's gratifying to see the Si agree with my choice .... |
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| May-20-16 | | Razgriz: I was either a Knight Sac or a Bishop Sac to open up the middle for a push. I got the initial sacrifices but I couldn't get anything after that. |
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| May-20-16 | | mel gibson: The computer doesn't play the same moves.
It plays
31. Rb7 Nac8
32 Nxc5
& the 2 passed pawns get broken up & one lost with a black Knight sacrifice.
White still wins. |
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| May-20-16 | | whiteshark: I knew the motif from
- the black side
- hours of in-depth analysis
- here: Team White vs Team Black, 2015 |
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| May-20-16 | | not not: too hard for me, I was thinking about Rb7 bulling the knight into passive position, and then Rb8 increasing pressure knight sacrifice did not enter my mind |
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May-20-16
 | | Sally Simpson: It's one of them puzzles where you must be honest with yourself. Would you have gone for it in a game without the hint 'stop here...White to play and win.' Here of immense value to a student are games not where the combination was played, but in games where one was missed. Your task there is to skip through the note less game and spot the shot. This builds up your ability to recognise a critical position. Of course knowing something was missed heightens your awareness, you have been given a clue, but you should be in this state of awareness when playing. (much easier said than done.) Anyway...Back to this one and if we peel back one move before the Knight sac. (which we have been given the strong hint that something drastic is on.) White has just played 30. Rg1-b1 leaving the g-pawn hanging. 
click for larger viewThis move clearly has designs on the loose a7 Knight and it lack of squares. If 30..Rxg5 then 31.Rb8 covering c8 then Nb6, protect it with the a-pawn or a Bishop and that a7 Knight is in trouble. There does not appear to be too much Black can do to stop this but sit and watch as he loses a piece in broad daylight. In this line after 30...Rxg5 the Knight sac on c5 is is no longer on as the Rook on g5 holds the e5 pawn. Black did not take the g5 pawn and sensing the danger played 30...Ne7 (covering c8 meeting Rb8 with Na-c8). This took us to here...
click for larger view...then came the Knight sac on c5 to get the pawns rolling. This was intuition, 100% concrete analysis is beyond reason. But it's not too hard to spot. Black's position was ripe for a strike of this nature. As mentioned all that need be was the 'Leap of Faith' and to look out for Black saccing back, which he tried to do with 39...Rxc4. 
click for larger viewWhite ignored it and played 40.Bxg6+.
Good Game. |
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| May-20-16 | | YetAnotherAmateur: <patzer2> Thank you for the engine help. My approach was: 31. Rb7 Nc8
32. Nxc5 dxc5
33. Bxe5 Rxg5
34. Bxf4 Rg4
35. Ke3
and now white has everything he needs to push the d or e pawn home, and black has no real options left. |
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| May-20-16 | | kevin86: The knight sac gets the ball rolling. |
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| May-20-16 | | YouRang: My answer for today's puzzle was:
"It probably involve sacrificing a piece for 2 pawns to get connnected passers in the middle of the board". Worth partial credit? |
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Kibitzing
sac: 31.Nxc5
