George Duke wrote on Thu, Apr 25, 2013 01:12 AM UTC:
This is another classic score where the correction is not even the second
or third move after the definitional brilliancy,
http://www.chessgames.com/perl/chessgame?gid=1284171, but the very first
move after. 'Find that locus and make the right move' would not seem to
be insignificant discovery. So here upon Move 21 Nxe6..., Black has at
least one winning move to replace 21 ...Nxf1.
The difficulty this case is Move 21 replacement has half a dozen best candidates. Which one most justifiable then, where Black goes wrong?