17...Qxb3 18.Qxb3 cxb3 was a safe alternative, where Black just keeps his extra b-pawn.
A questionable decision. Now Black's king becomes a strong piece instead of a vulnerable one, and eventually Lima managed to convert his extra pawn:
What move would you play here? The natural and obvious 14...Nc4? What candidate moves did you choose between? You probably also considered several rook moves. Fischer, however, opted for...
Indeed, hardly the first move you would think of Prophylaxis against a possible knight sacrifice on e6, perhaps?