Rama: This becomes a tense struggle. Is there such a thing as a prepared variation in the Caro? The white Knight makes 5 of white's first 11 moves. With 13. ... Nbd5, black looks equal, to me. After 17. ... Rfe8, both sides are fully centralized and play shifts to the Q-side.
18. ... Qc8, threatens 19. ... Ba6, which white cannot comfortably parry with the c-pawn because of the pin; yet he needs that square for the pawn. Therefore 19. Ba4 ..., and it can still interpose on b5 if need be.
On 20. dxc5 ..., it would seem that recapturing with the Bishop would have been better. It can be kicked with b4 but does white want to play such a move? The c-pawn objects! 20. ... bxc5, creates permanent weaknesses.
22. Bd3 ..., shifts play temporarily from the Q-side back to the center where mass carnage ensues starting with 25. ... Nxe5.
29. ... Be4, is clever but cannot conceal the weakness of black's Q-side pawns. With 34. Rxc5 ..., Spassky begins dissecting Benko's position.
42. Rd7 ..., threatens a discovered attack on the Knight, so the piece must move. This gives white time for c5-c6-c7 in quick succession.
The pawn queens and white emerges a piece up -- the Bishop triumphs at last -- with pawns to spare. Benko resigns.
Benko hung himself with the pawn-move; Spassky was cool enough and professional enough to make it count.
Kibitzing
