WITHIN A FEW DAYS, barring a miracle, Gary Kasparov will end his merciless dissection of Anatoli Karpov at Moscow's Tchaikovsky Concert Hall and win the world chess championship. The American Psychological Association would do well to study the confrontation in depth.

So much of what Gary Kasparov knows about chess and psychology he learned from his childhood idol, an eccentric American genius named Bobby Fischer.

After demolishing the spirit and game of the Soviet Union's Boris Spassky at the world championships 13 years ago in Iceland, Fischer forfeited his title to Karpov, and vanished from the public world. Now he is only a collection of rumors, a ghost haunting Tchaikovsky Hall.

When Fischer was still playing he was one of the most admired foreigners in the Soviet Union. A state farm in Siberia even named a prize heifer Bobby. While Fischer is alive, Kasparov knows that when he becomes champion, his achievement will be marked by a bold asterisk.

Kasparov's clear, attacking style derives from Fischer, as does his talent for mind games. Fischer made a wreck of Spassky in Iceland, first by making impossible demands before the match ever began and then by pulling a surprise opening move so unlike anything he had ever tried before that he left poor Spassky and his towel boys saucer-eyed.

Kasparov, 22, a half-Jewish Armenian and an iconoclast to the Soviet chess establishment, has never revered Karpov, never paid his fellow countryman much respect.

Their first match was canceled after an epic series of draws. In the re-match Kasparov has plumbed not only Karpov's subtle defensive game, but also his tender psyche. He showed his disdain by refusing to speak to Karpov and by revealing sealed moves -- the equivalent of Muhammad Ali grinning, wiggling his fanny and daring George Foreman to take his best shot. Karpov's misplays revealed a man unwound, the simulacrum of an earthling freaked by an extraterrestrial.

But no one in the world of chess has claimed Kasparov as the new Fischer. Then again, few would want to be the Fischer of today.

For several years after beating Spassky in 1972, Fischer led a hermit's life in Pasadena, Calif. as an adherent of a fundamentalist sect, the Worldwide Church of God. He has left the church but but not his strange isolation.

According to a long story in Sports Illustrated this year, Fischer told a friend that he had a dentist remove all the fillings from his teeth because he feared outside forces might "influence (my) thinking." He became a great believer in esoteric medicines: Mexican rattlesnake pills "for general health" and Chinese brain pills to ease his headaches. Fischer, whose mother is Jewish, is also an anti-Semite, said SI, talking about "kikes," gold conspiracies and the "myth" of the Holocaust.

There is a long tradition of eccentrics in chess. Ernest Jones, Freud's colleague and biographer, and Reuben Fine, a chess grandmaster and psychoanalyst have written of Paul Morphy, who died of a chill in a bathroom filled with women's shoes; of the Russian champion and ardent anti-Semite Alexander Alekhine, who moved to Germany during World War II and made speeches "proving" that Jews could not play chess; of Wilhelm Steinitz who believed he could make telephone calls without wire or receiver and who said that he was not only in electric communication with God, but could also beat Him in chess conceding a pawn and the first move.

And there was the theoretician Nimzovich who once complained to a referee that an opponent was smoking. "He's not smoking," said the referee. "Yes," said Nimzovich, "but he's thinking about it."

Marcel Duchamp, the Dadaist and chess enthusiast, once said that chess players are "completely cloudy, completely blind, wearing blinkers. Madmen of a certain quality, the way the artist is supposed to be, and isn't, in general."

In his novel, "The Defense," Vladimir Nabokov, another passionate amateur, portrayed a genius named Luzhin whose obsession with the game is so blinding that when he finally jumps out a window the street below him seems a landscape of "dark and pale squares."

Fischer is the real-life Luzhin, still the king of chess and chess eccentrics. With an IQ of 184, he dropped out of school "because the stuff they teach you in school I can't use one way or the other." He developed his talent, thrilled the world with a singular recital and left the stage for cheap hotels.

When Fischer destroyed Spassky, he became a hero to a generation of players. Lubomir Kavalek, a Czech expatriate and grandmaster who lives now in Reston, says, "Bobby was, and still is, a living legend. Everyone began playing. He was an inspiration. Without him, we're back to the Dark Ages. There's no one around to take Bobby's place."

When I visited the match in Moscow a few weeks ago as a tourist, I met two old men in weary suits and dun fedoras. They stood in the foyer of the Tchaikovsky Concert Hall snacking on sturgeon sandwiches and pear-flavored soda. Inside, Karpov was spellbound by Kasparov's preternatural skill. But the men were not talking much about Karpov or Kasparov or anyone else likely to play the game in public ever again. They were talking about Bobby.

"You are American?" one of the men asked. "You must tell us. What has happened to Bobby Fischer?" I knew the word for "out-of-one's- mind" ("soo-ma-shed-shi") but it was not so easy to relay the details of Fischer's abdication.

"We still hope he comes back," one of them said. It seems now that it will never happen.

"All I want to do, ever, is play chess," Fischer once said. But he no longer does. There are reports, here and there, that he keeps up with the game and still plays with his old lucidity and brilliance. But Fischer does it all in secret.

Gary Kasparov would do best to cease his imitation of the Fischer saga at 1972. All the rest is too sad, too weird.