NOT SINCE Bobby Fischer noisily won the world chess championship and then quietly dropped out of sight in 1972 has there been an exhibition of disciplined savagery to equal what Victor Korchnoi has been doing to the Russians this year. In 1976, the aging grandmaster seemed past his peak, doomed to recede slowly into a minor niche in the chess pantheon as one of the great ones who nearly made it to the top. Then he left the Soviet Union, declared war on his former country's chess bureaucracy and through most of this year he has been slaughtering the best players they can send against him.The change of climate, from Russia to The Netherlands, has done wonders for him.

A former world champion, Tigran Petrosian, was his first victim; then an old friend, Lev Polugaevsky. Now he is pushing an old friend and former world champion, Boris Spassky, down the road to the slaughterhouse. The world championship candidates' final match in Belgrade is not over, and Spassky could still theoretically win, but only a miracle can keep the current match from becoming a lopsided Korchnoi victory.

Spassky is already one of the game's immortals; most experts would rank him, at his best, among the half-dozen greatest players who ever lived. And he has fought stubbornly, often brilliantly, but he has made small mistakes and they have been enough to give Korchnoi a runaway margin.

Korchnoi's ultimate target is Anatoly Karpov, who inherited the world championship without playing a single game against incumbent Fischer when Fischer refused to defend his title in 1975. Korchnoi and Karpov had their previous showdown just three years ago in a hard-fought 24-game match that Karpov won by a single point. Now, Korchnoi claims he was under heavy psychological pressure from the Soviet chess bureaucracy not to win that match; he has escaped the jurisdiction of the bureaucracy, and it looks like he will have another crack at Karpov outside Soviet territory next year.

Korchnoi's maneuver against the Soviet bureaucracy resembles the gambits played in some chess openings, where a player sacrifices material to get an advantageous position. Korchnoi has sacrified his Russian citizenship and the considerable income and prestige that strong chessplayers enjoy in the USSR to get a clear shot at the championship. His first four victories against Spassky, given below, show how well he has used that opportunity so far.