Dec0404   DanielBryant: Nice sacrificial attack, esp. 19.Rd1. Does this seem sound to the rest of you? 

Mar1912
  FSR: Living Large. 

Feb2114
  SwitchingQuylthulg: The sacs seem to be completely sound, though my engines hate them to begin with. Here's one line with a very weird move repetition... click for larger view23...Qd8! (attempting to plug the hfile at any cost) 24.f5! Bg5 25.f6! Bh6 (25...Bxf6? 26.Bxf6 Qa5  there's nothing else  27.Bd5! Qd2 28.Bxa8 and White wins) 26.Rxh6! gxh6 27.Qh4 e5 click for larger view28.Bb6 Kh7 29.Be3 Kg8 30.Bb6 draw. 

Jul0917
  offramp: click for larger view
White's queen's rook went up to d4, where it can sometimes come in handy. But it was in the wrong place!
So White...
click for larger view
had to laboriously
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bring it back around to h1. 

Jul0917   EhsanBalani: What kind of move is 22.Bd4?
Why didn't play: 22.Qh3? 

Jul0917
  Check It Out: <User: EhsanBalani> If 22.Qh3 then black can play 22...f6, giving his king a nice escape path. 22.Bd4 attacks the vital a1h8 diagonal, with particular pressure on g7 and e5. What I don't understand is why black played 23...f6, allowing 24. Qxg6 with a crushing position. 

Jul0917
  morfishine: Yes <Check It Out> the miserable <23...f6> is just Black tossing in the towel ***** 

Jul0917
  AylerKupp: <EhsanBalani> 22.Qh3 (part 1 of 2) According to Stockfish 8 at d=40, if 22.Qh3 Black has no more than a draw by repetition: 22 ..f6 23.Bxe6+ Bxe6 24.Qxe6+ Rf7 25.Qh3 Rff8 26.Qe6+ etc.
click for larger viewStockfish considers 22...f5 as slightly better and allows the escape that <Check It Out> suggested. Stockfish evaluates it at [0.74], d=40 after 22...f5 23.Bd4 Kf7 24.Bxg7 Qc5 (I think that this would be a hard move to find OTB, but it is the key to Black's defense) 25.Qh7 Ke8 26.Qxg6+ Kd8 27.Bxf8 Bxf8 28.Qf6+ Be7 29.Rh8+ Kc7 30.Qxe7+ Bd7 31.Rh1 (and because of 24...Qc5 the rook must retreat to stop the mate at g1, allowing Black to activate his rook and get the needed counterplay) 31...Rg8 32.bxc3 (forced, because once more the mate at g1 is threatened) 32...Qxc3 33.Kb1 Rg7 34.Qf8 (but this allows Black some counterplay) 34...fxe4 35.Qa8 e3 36.Qa7+ Kd8 37.Qxa6 Ke7 38.Qa8 Qd4 39.Qf3 Qd2 40.Qe4 Qg2 41.Qxg2 Rxg2 42.Kb2 Kf6 43.Kc3 Kf5 44.Kd3 Rg3 45.a4 Bc6 46.Rh6 Be4+ 47.Ke2 d5 48.c3 Kxf4 49.Rh4+ Kg5 50.Rh8 Kf6 51.a5 Bf5 52.Rh1 Bg4+ 53.Kd3 e2+ 54.Kd2 d4 55.a6 Rxc3 56.Rh6+ Kg5 57.Bxe6 Kxh6
click for larger viewBut this is lost for White since after 58.Bxg4 Rc2+ Black mates in 15 according to the Lomonosov tablebases. White's relative "best" per Stockfish is 59.Kxc2 e1=Q 60.Bxg4 Qe4+ 61.Kd2 Qxg4 and this is clearly lost for White. And the positions are razor sharp and one inaccuracy can change the outcome. For example, Stockfish evaluates 22...cxb2+ 23.Kb1 as allowing a draw by repetition after 22...cxb2+ 23.Kb1 f5 24.Bd4 Kf7 25.Bxg7 Qc5 26.Qh7 Ke8 27.Qxg6+ Kd8 28.Bxf8 Bxf8 29.Qf6+ Kc7 (I'm not sure why not 29...Be7 as in the line following 22...f5) 30.Qxf8 fxe4 31.Rh7+ Kb8 32.Bxe6 Qg1+ 33.Kxb2 Qd4+ 34.c3 Qf2+ 35.Kb1 Qe1+ 36.Kb2 Qf2+ etc.
click for larger viewIt seems that White's king is safer on b1 than on c1 and that, in order to prevent a back rank mate, White must spend a move with b2xc3 to provide an escape for his king. And in a position like this one, one lost tempo can make all the difference. 

Jul0917
  AylerKupp: <EhsanBalani> 22.Qh3 (part 2 of 2) And Komodo 11 agrees with Stockfish's evaluations. At d=35 Komodo's first line after 22...f6 is the same as Stockfish's, leading to a draw by repetition. And after 22...f5 Komodo initially follows Stockfish's line and then deviates, evaluating the resulting position as pretty much equal, [0.49] after 23.Bd4 Kf7 24.Bxg7 Qc5 25.Qh7 Ke8 26.Bxf8 (here Komodo deviates from Stockfish's line after 25...Ke8 but it's just a move transposition) 26...Bxf8 27.Qxg6+ Kd8 (now we're back to Stockfish's line after 27...Bxf8) 28.Qf6+ Be7 29.Rh8+ Kc7 30.Qxe7+ Bd7 31.Rh1 Rg8 32.bxc3 Qxc3 33.Kb1 Rg7 34.Qf8 fxe4 35.Qa8 e3 36.Qa7+ Kd8 37.Qxa6 Ke7 38.Qb7 (and only now does Komodo deviate from Stockfish's 38.Qa8) 38...Qc6 (Stockfish could also have forced the exchange of queens by 38...Qc6, once again reaching the same position) 39.Qxc6 Bxc6 40.Re1 Rg3 41.Kb2 Rf3 42.Kc3 Rxf4 (this seems to lead to an equal position) 43.Rxe3 d5 44.Kd3 Bb5+ 45.Kd2 Kd6 46.a3 Rh4 47.Rg3 Ba6
click for larger viewIndeed, restarting the analysis from this position at d=36 Komodo evaluates the resulting position as even, [0.00] after 48.a4 Rh7 49.Rg8 Rc7 50.Ra8 Bc8 51.c3 Bd7 52.Ra6+ Kc5 53.Bc2 e5 54.Bd3 Rb7 55.Ra5+ Kd6 56.c4 d4 57.c5+ Kc7 58.Bb5 e4 59.Ra6 Bxb5 60.axb5 Rxb5 (and this position is a theoretical draw per the Lomonosov tablebases after 61.Rd6) 61.Ra4 e3+ 62.Kd3 Rb3+ 63.Kxd4 e2 64.Ra1 Rb4+ 65.Kd3 Kc6 66.Kxe2 And after 22...cxb2+ Komodo comes to the same conclusion as Stockfish, a draw by repetition after 23.Kb1 f5 24.Bd4 Kf7 25.Bxg7 Qc5 26.Qh7 Ke8 27.Bxf8 Bxf8 28.Qxg6+ Kd8 29.Qf6+ Kc7 30.Qxf8 fxe4 31.Rh7+ Kb8 32.Bxe6 Qg1+ 33.Kxb2 Qd4+ 34.Kb1 (here Komodo deviates from Stockfish by omitting 34.c3 but it makes not difference) 34...Qg1+ 35.Kb2 etc.
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Jul0917
  RandomVisitor: 23...f6 was the losing move, as <Check It Out> says. Maybe 23...Qd8 was better, but the machine at low ply is calling the position even. 

Jul0917
  AylerKupp: <<Check It Out> What I don't understand is why black played 23...f6, allowing 24. Qxg6 with a crushing position.> Yes, after 23...f6 24.Qxg6 represents, as <morfishine> said, Black tossing in the towel. But as you can see in my response to <EhsanBalani> above, Black effectively tossed in the towel (as far as getting a win) earlier with 22...cxb2. Only 22...f5 gives him possible winning chances providing that he can find all the perfect responses to White's moves, and that White does not find the best continuations. No offense meant but I frankly doubt that Muir would have been able to calculate all the needed variations or even stumble upon them. Maybe Korchnoi or Petrosian, both renowned defensive players, might have. 

Jul0917
  RandomVisitor: Stockfish likes 22...Qd8! 

Jul0917
  RandomVisitor: After 22...Qd8 black plans Bh4 to block up the hfile. click for larger viewStockfish_17061704_x64_modern: <1 hour computer time> <2.55/44 23.Kb1 Rb8 24.Qh2 Bh4 25.Bf2 g5 26.fxg5 Qxg5 27.Bxh4 Qh6> 28.Qg2 Rb5 29.Be7 Rh5 30.Rg1 Re8 31.Bxd6 Bb7 32.bxc3 Qh7 33.Kb2 Bxe4 34.Qf2 Rh1 35.Be5 Bg6 36.a4 Rxg1 37.Qxg1 Qh5 38.Qe3 Rd8 39.c4 Qh6 40.Qg1 Qh4 41.c5 Rc8 42.Qe3 Qg4 43.Qc3 Be4 44.Qd4 Qf5 45.Bd6 Rd8 46.Bc4 Bxc2 47.Bxa6 3.90/43 23.bxc3 d5 24.Kd1 a5 25.f5 exf5 26.Qh2 Bh4 27.Bxd5 Ra6 28.Qxh4 Qxh4 29.Rxh4 Rd8 30.Kc1 fxe4 31.Bc4 Rc6 32.Bb3 Bf5 33.Rf4 Rcd6 34.a3 a4 35.Bxa4 Ra6 36.Bb3 Rxa3 37.Kb2 Ra6 38.Rh4 Rdd6 39.Rf4 Ra5 40.Be3 Rd1 41.Rf2 Ra6 42.c4 Be6 43.Rg2 Rh1 44.Kc3 Rh3 45.Kd4 Rd6+ 46.Kc5 Rd1 47.Rd2 Rxd2 <4.23/43 23.Qh3 Bh4 24.Qxh4 cxb2+ 25.Kxb2 Qxh4 26.Rxh4> Bb7 27.e5 dxe5 28.fxe5 Rfd8 29.c3 a5 30.Bc2 Bd5 31.Rh3 Rab8+ 32.Ka3 Rdc8 33.Bd3 Ra8 34.Bc2 Bc4 35.Rg3 Rab8 36.Bb3 Rb7 37.Ka4 Bf1 38.Ka3 Be2 39.Rh3 Bb5 40.Bc2 Bc4 41.Rh2 Rbb8 42.Be4 Rd8 43.Bc2 Rb5 44.Be4 Bd5 45.Bd3 Rbb8 46.Rh3 
