|NeverAgain: • 21...Rxb5 - I looked at the Queen sacrifice <21...Nxc3> suggested by Atking, but it doesn't seem to give Black nearly enough compensation. The black LSB can rule the long light diagonal, but there are no targets there, and White's kingside pawn wedge hinders its redeployment to target the white king.|
So, <21...Nxc3 22.Bxe8 Nxa2+> and now White has two alternatives.
a) The simple <23.Kc2> is good enough: <23...Rxe8 24.Rhe1 Nb4+> (24...Ba6 25.Bd2 Bc4 26.Re3) <25.Kb1 c4> (25...Bc6 26.Qe3) <26.e6 c3> (26...exf6 27.Qxa7 Rb7 28.Qa4) 27.exf7+ Kxf7 28.Ka1 Rb5 29.bxc3 Bf6>
click for larger view
<30.Qb2 Rxe1 31.Rxe1 Ba6> the Bishop comes into play at last <32.Bd2 Ra5+ 33.Kb1 Bc4> and here White should give back the Queen and go into an endgame where he is up an exchange - <34.Qxb4 Rb5 35.Kc2 Rxb4 35.cxb4 >.
b) <23.Kb1!> is the cunning plan. The idea is to clamp down on the black King at the price of an exchange: <23...Nc3+ 24.Kc2 Nxd1 25.Bxf7+!> the point <25...Rxf7 26.Rxd1 Rb4 27.Qe3 Rf8 28.e6>
click for larger view
The white kingside wedge is like a fishbone in Black's throat. The Bishops cannot move, as the LSB has to guard d7 and the DSB e7, the kingside Rook is cut off behind them, and Black cannot very well attack with just the queenside Rook. He cannot sit and wait either, as White will simply set his kingside steamroller in motion with Qe5, g5 and f6.
At this point the engines give a couple of checks, putter around a bit, acknowledge running out of ideas and sac an exchange just to get some air - <28...Rc4+ 29.Kb3 Rb4+ 30.Ka2 h6> pointless and weakening <31.h3> tit for tat, White now threatens 32.Bxh6 too <31...Rxf4 32.Qxf4 Bxe6+ 33.Kb1> and with a Queen for two Bishops the win is just a question of time.
• 23...Bb7?! - too slow and drives the white Rook where it wants to go. It was high time to do something about White's kingside threats, and once again tactics could come to Black's help:
<23...Bh4!> - Black forces the exchange of the DSBs which takes most of the sting out of White's kingside attack <24.Qxh4 Rxh4 25.Qg3 Rd4 >. White can't avoiding the exchange as <24.Qe3> can be met with <24...f6>, completely neutralizing the wedge, e.g. <25.e6 Rxf4! 26.e7> (26.Qxf4?? Bg5 ) <26...Rxf5! 27.exfQ+ 28.Kb1 Re5=>.
You gotta agree that <23...Bh4> would have been a nice counterpart to <21.Bb5>
• 24...Kh8 ? - Black's other big mistake, a thoroughly incomprehensible move that does nothing to improve the King's defence and gives White an extra tempo for his attack. Black had to try <24...Qc8 25.f6 gxf6 26.Bh6 Qe6>. After the blunder in text White's attack was irresistible.
So no, this was no walkover for Fischer, he didn't win this game by sheer brilliancy. In fact, had his opponent not missed a couple of good moves, Bobby could indeed have had some headache.