complete game
variation from 18.Bxb6,
if white takes bishop: 18.Bxe6,then black mates in 5
VARIATION
after 11....Na4 offering the knight, this can happen if White takes 12.Nxa4
In post #1, Fischer's line is actually mate in 6. Can you find the real mate in 5?
actually there is also different line to mate with only bishops and rook
20.Nd4+ ...
what can happen if W blocks check with the rook ?
actually there is also different line to mate:
36...Ng3+ 37. Ke1 Re2+ 38. Kd1 Bb3+ 39. Kc1 Ba3+ 40. Kb1 Re1# is quicker.