Victor Korchnoi snatched a draw from the jaws of defeat in the 22nd game of his world championship chess match with Anatoly Karpov, wiping out his opponent's kingside pawns, neutralizing the passed pawn on the queenside and avoiding the exchange of rooks that might have given Karpov a final chance to squeeze out a victory.
The 47th move sealed by Korchnol for the game's overnight adjournment was the one predicted by most experts, PxP, but Karpov interposed his bishop, blocking the black rook from queenside action, so Korchnoi returned to the defense of his embattled knight. On move 50, the 47-year-old challenger offered a knight sacrifice which would have assured him of a draw after 51. RxN, P-N8-Qch; 52, KxQ, RxB, but Karpov prudently chose to take the threatening pawn instead of the knight, and the black knight was able to return to action, first taking a pawn and then being posted to sentry duty on the queenside.
Black's mysterious rook moves from moves 57 to 60 represent Korchnoi's effort to avoid a forced exchange of rooks. If 57 . . . RxP; 58, R-R2, RxR; 59. BxR, black's position suddenly becomes menacing again; the kind can penetrate to the back ranks, drive the black knight away and ease the QRP's way to queenhood. Once the white bishop is driven back to the second rank, the pawn can be taken safely.
A variation of the same threat is implied in Karpov's 63. R-R4, which is why Korchnoi moved his king back out of the line of fire. Once the prospect of a rook exchange had been averted, Karpov's winning chances were gone (if anything, Korchnoi may have a slight edge in the final position) and both players agreed to a draw.