Plosh, plosh, plosh, Victor Korchnoi, dogged in everything, plowed through the muddy turf of the Baguio County Club golf course, his elbow swinging wide as he ran to keep his 47-year-old body in shape.

For the challenger in the world chess championship, three laps around the soggy first hole provided good practice for a long, drawn-out contest still slogging through political and psychological quicksand. He is behind, four wins to one, but his play is improving and it may be a while before anyone reaches the magic six wins, since draws don't count and interruptions are many.

Korchnoi, a recent Soviet defector, has in the space of eight eventful weeks threatened to punch out a Soviet psychologist, has protested his opponent's taste of yogurt and has spent the last few days meditating with American members of an Indian religious sect who were recently convicted of attempted murder.

The world champion, Soviet Anatoly Karpov, 27, has unnerved Korchnoi by rocking in his chair to some unheard disco beat, has gone deep into hiding behind a phalanx of armed security guards and has stationed his bug-eyed psychologist where he is likely to drive the already paranoid Korchnoi completely mad.

To some outsiders, both of these men, due to split $550,000 dollars in prizes, might seem certifiable candidates for psychological counselling. Despite spending five hours every other day enegaged in the most intimate mental combat, they have not spoken a word to each other since Aug. 8.

But to this town temporarily loaded with chess insiders, it's all part of the great game of Shakhmat, as the Russians who so dominate the game call it. Chess has become the No. 1 industry this summer in this mountain resort, built 70 years ago for the comfort of the then U.S. colonial administrators. Politics runs a close second.

Korchnoi, finished with his run around the golf course, settled himself on the country club terrace and read to his entourage his latest angry letter to the match organizers. Philippine authorities had recently banned from the playing hall the two members of the Ananda Marga sect who were out on bail after the attempted murder conviction. Korchnoi, with gestures and laughter, defended his two friends Victoria Sheppard and Stephen Michael Dwyer, and noted with disapproval the presence in the hall of members of the infamous Soviet intelligence froce, the KGB.

Petra Leeuwerik, a 49-year-old Austrian woman who spent several years in a Soviet prison camp for allegedly spying for the United States, smiled encouragement at the man she has been with almost constantly since her recent separation from her husband, Korchnoi has demanded several times that the Soviet government let his own wife and son, still in Russia, leave the country. Said one Russian after a particularly bitter Korchnoi blast at Moscow: "I wonder how he'd like it if we sent his wife here?"

The political fireworks, and other strange things about this match, might be blamed on an American living in seclusion somewhere in Pasadena, Calif., 8,000 miles away. He is Robert J. "Bobby" Fisher. To Korchnoi, and perhaps to several of the Soviets here including the uncommunicative Karpov, Fischer remains the best chess player in the world. He forfeited his title in 1975 without playing a game after he refused to accept International Chess Federation rules for a championship match with Karpov.

Fischer's devastating defat of Soviet champion Boris Spassky in Reykjavik, Iceland, in 1972 in a way led to Korchnoi's defection. Korchnoi said the Russians became so obsessed with finding a suitable challenger to Fischer that they devoted all their attention to the young and promising Karpov and slighted older players like Korchnoi. Korchnoi defected while attending a match in Holland in 1976. Then seeming to sip from some fountain of youth, he stunned the chess world and enraged Moscow by winning a series of championship qualifying matches at an age when most chess grandmasters sit quietly at home annotating the memorable games of their youth.

So here on this Asian island the final contest began between Soviet loyalist and Soviet defector, a conflict more hate-ridden and politically charged than even the 1972 contest between Fischer the American and Spassky the Russian.

That earlier championship, however, laid the ground for the circus atmosphere of high-money stakes, world media attention and wild psychological maneuvering that has heated up these cool mountain slopes this summer. Fischer's stunning victory in 1972 after more than 20 years of Soviet dominance turned chess overnight into a big-money, international sport.

Harry Golombek of The Times of London, author of 38 books on chess, said royalties doubled after Reykjavik. Cities began to offer huge purses. The winner here will receive $350,000 and the loser $200,000, both more than Fischer's winning share of about $156,000 in 1972. Players saw the advantages of Fischer's own prematch histrionics, which had always been discouraged by the Soviets during the years they controlled the championship.

World class chess players, masters of a game of egos, love to indulge in odd behaviour. In the last qualifying match leading to Baguio, Spassky, attempting a comeback, took to wearing a sun visor or underwater goggles, and spending time away from the chessboard sitting in a specially constructed box.

Korchnoi also retreats to his own world. At the country club he ordered his usual 3 p.m. light lunch, while one of his young seconds, English grandmaster Michael Stean, 25, started a game of "Othello," a popular offshoot of "Go." with Edmund Edmondson, former head of the U.S. Chess Federation and one of the three match judges. Korchnoi basked in the recent memory of a remarkable save of the 20th game in the series. He had forced Karpov to accept a draw after Stean and others told reporters that Korchnoi's position was hopeless.

"Victor, I had some ideas last night," said Stean, his eyes remaining on the "Othello" board.

Korchnoi gave Stean a malevolent smirk. "Oh, new thoughts on the 20th game?"

Stean, undaunted, began to outline in rapid chess shorthand. What Karpov could have done to win. "No, no," said Korchnoi, unconvinced.

"It's lost that way," Stean insisted. "No, now wait, Michael."

Stean moved a few "Othello" pieces. Korchnoi stared into space, lost in the problem. Leeuwerik, a bubbly, friendly woman, mentioned to Korchnoi that a small boy had come up behind to get his autograph. Korchnoi maintained is blank look, taking the paper and signing it without looking at or speaking to the child.

Lunch had not come yet, but it was time for Korchnoi's afternoon nap at a secluded villa used for strategy sessions. He and Leeuwerik left, leaving a reporter to eat the challenger's celery soup and crackers.

Sheppard and Dwyer were banned but other members of their flock were allowed to join the small audiences of about 100 to cheer Korchnoi on silently. Behind the scenes the challenger's aides bickered over the affair, with English grandmasters Stean and Raymond Keene, 30, trying to keep Korchnoi's mind on chess while Leeuwerik reveled in the controversy.

In line with previous championships, the contestants lead a nocturnal existence. They rise around noon, exercise, nap, and then begin strategy sessions or the match itself about 5 p.m., the matches falling on Tuesdays, Thurdays and Saturdays. Games always adjourn, even if not finished, about 10 p.m. The participants eat dinner and spend the rest of the night celebrating, grieving or pondering how to win an adjourned game.

While Korchnoi and his seconds are often accessible when not hatching strategy, Karpov spends most of this time walled off in a suite in the Terraces Plaza Hotel. He emerges only for tennis or the matches themselves. "Once I told Karpov there was a girl in Baguio who wanted to play tennis with him, which is true," said Stean. "He said 'I play with my trainer.'"

Karpov's chief protector is Viktor Baturinsky. At 5 feet tall and 200 pounds, he does not look like the hard-boiled former KGB prosecutor he is reputed to be Baturinsky is the vice president and actual head of the Soviet Chess Federation, the president being a former cosmonaut. "An interview with Karpov will of course be impossible," Baturinsky said, through a young, leather-jacketed interpreter. "But we might be able to arrange something with some other member of the delegation, in principle."

Gossip among the 20 or so reporters hanging on here for the long haul centers around how to get Karpov. Sports Illustrated magazine scored a triumph early in the series, getting to talk to Karpov allegedly through the efforts of a Russian-speaking photographer and offers of blue jeans and rare stamps, two of the champion's few known weaknesses.

"Many people in the West think I'm a cold player, but that's not true," Sports Illustrated quoted Karpov as saying. "But particularly with Korchnoi, if one remains calm, he can't stand it. It is an act to get him to blow up. Maybe in this match he'll be calm and I'll go crazy."

Since the games began July 18 the two sides have fought over flags (the Soviets protested Korchnoi using a Swiss flag, so all flags were removed from the playing table), chairs (Karpov said Korchnoi's was too high), yogurt (Korchnoi said Karpov's mid-match snack might be a strategy signal, depending on the flavor given him) and eyeglasses (Karpov said Korchnoi's threw light on the board.)

All that was nothing compared to the storm over Karpov's personal psychologist, Vladimir Zoukhar, Zoukhar's job is apparently to help the champion handle the pressures of world-class competition, since the very honor of the Soviet Union is ridding on his slim back. But the Russians had Zoukhar sit in the first few rows of the playing hall. Although the large hall is kept dark with lighting only on the stage where the players sit, Korchnoi could see Zoukhar's odd, intense stare. The Russians knew about Korchnoi's fears of long-range hypnosis so the psychologist's presence seemed calculated.

"I will give you 10 minutes to shift that man, otherwise I can do it with my own fist," Korchnoi shouted from the stage at the beginning of the 17th game. Match officials moved Zoukhar a few rows back. Korchnoi lost the game, his fourth loss, and went off to Manila where he stayed until a compromise was reached. He gave up his reflecting glasses in return for Karpov's agreement to move Zoukhar far to the back of the room, out of sight.

While in Manila, however, Korchnoi met members of the Ananda Marga sect who convinced him their meditation methods could ward off whatever bad vibrations the Russians were emanating. They returned to Baguio with the challenger, quitely instructing him in meditation and creating consternation among the Philippine officials. Two of the sect members, Sheppard and Dwyer, were out on bail from a conviction for knifing an Indian diplomat. The incident appeared to be part of a world-wide champaign of violence by the sect in retaliation for the jailing of its leader in India on murder charges.

The Soviets complained about the Ananda Margas' presence and derided Korchnoi's complaints about Karpov's psychologist. Mikhail Tal, a former world champion and a key Karpov aide, said "it transpires that we have brought with us a magician-cum-hypnotist whose sole task is to disturb the challenger's thoughts."

Stean, hunched over the "Othello" board at the country club, indulged in some of the teasing that underlies much of the bickering here. Stean is lean and athletic, Korchnoi's regular companion in his daily rounds of Ping Pong and jogging. "It is my theory that Zoukhar is a patient in a mental institution. They felt as part of his therapy they would let him out for awhile," he said.

Stean said he had little use for Ananda Marga, "if those people didn't have a very good effect on Victor, as they have, I would get rid of them myself . . . at least Victor thinks he has a defense (against Zoukhar) so he feels better."

Edmondson, the friendly American judge, flipped the last pieces on the "Othello" board. Stean, to his dismay, had lost, despite a far superior position.

"It's those bloody Ananda Marga," he said.