Black American boxer John Tate and white South African Gerrie Coetzee will battle for supremacy as World Boxing Association heavyweight champion Saturday (WRC-TV-4, 4:30) in the heartland of the country that has come to personify racial conflict.

More than 80,000 South Africans of all races will stream into Loftus Versfeld rugby stadium in this country's administrative capital of Pretoria to watch Coetzee attempt to become the first white boxer in 20 years to win the WBA title. Ingemar Johansson took the title from Floyd Patterson in 1959.

Augmenting the live adience, the largest at a championship fight in more than half a centruy, will be millions of overseas television viewers. Among the ringside rooters in Pretoria will be South African Prime Minister Pieter W. Botha and several cabinet ministers.

Police in Pretoria, usually a quiet town of half a million residents with a preponderance of civil servants, are girding for the biggest event they will have had to handle outside of the rioting in black communities in 1976 and 1977. Police authorities pleaded with people not to bring liquor or weapons into the stadium. The winner of Saturday's night's fight likely will meet Larry Holmes for the undisputed world championship.

The fight has given white South Africans an almost euphoric respite from the stream of hostility they usually encounter in international sporting events because of their official segregationist policy of apartheid. And as the biggest sports drama in this country's history it also is providing a welcome relief from this country's worst polictical scandal, which has dominated the news for the past year.

In fact, the fight is the best news white South Africa has had since the gold price began to climb to more than $400 an ounce.

"All this making South Afticans feel good, and they haven't felt good in a long time," said one white South African.

For many, the fact that the fight is happening is a bit too good to be true.

"People are sitting with bated breath. They can't believe it is actually going to happen," said South African sportswriter Brian Ross Adams. "It's a mind-boggling event for a nation that can't even get a rugby tour off the ground . . . From a country which has nothing, suddenly they might have the king of the world."

But thieir eager anticipation at having a heavyweight champion may turn to gloom shortly after the fight begins at 10:30 p.m. South African time (4:30 p.m. EST).

In the last few days the odds against a Coetzee win have increased with a witchdoctor, tarot card reader, astrologer and a computer all predicting Tate will do in the South African. Betting in bars is putting even money on Tate, say press reports.

The fighters, both 24, have records too short to tell much about how they will fare, say most boxing observers. But the general feeling is that the two are a good match, with the 222-pound Coetzee's speedy and considered style pitted against Tate's strength and endurance. Tate has a 18-pound weight advantage.

Most of South Africa's 4.6 million whites consider the fleet-footed Coetzee a sure winner.

Among South Africa's "silent majority" -- the blacks -- a number will be cheering for Coetzee because he is South African. But many others are thinking along the lines of domestic servant Ernestine Majibe. Asked who she was rooting for, she pointed to her arm and replied, "Of course for this -- my skin."

Some blacks believe the fight is rigged and that the "outcome . . . is as concealed as a beacon."

According to The Voice, a black weekly, "It is a fact that the basic tenet of apratheid is the belief of white superiority over the black race. White South Africans and the Afrikaner in particular have down the years worked laboriously to prove this. Those years to sweat and frustration are going to be rewarded."

Loftus Versfeld Stadium is a holy of holies to the South African whites whose passion is rugby. At the insistence of promoter Bob Arum, who arranged the championship bout, the stadium was integrated first for this fight, and then for all time, as a condition for staging the fight in South Africa.

But this small victory for the American promoter was negated when the Afrikaner equivalent of the Red Cross, the Noodhulplisa, announced it would not let its black staff enter the ring the night of the fight, One-upped, arum flew into a rage (his second in this country) and banned the organization from the fight.

The black newspaper, The Post, commented: "There you are, Mr. Bob Arum, now you are really setting the true state of affairs in this nation . . . The only reason that racial integration (at Loftus) was allowed was simply a window dressing exercise aimed at selling this country's image overseas."

South African newspapers are giving fighters saturation coverage in stories that have dominated the front papges for the last two weeks. At their medical examination Tuesday, the rivals did not speak to each other, preferring instead displays of devastating eyeball contact.

"I won't waste my time trying to instigate a shouting or screaming match in public," Coetzee said. "I think these antics at weigh-ins and medical checks are childish."

Tate appears to be bearing the prefight tension better than Coetzee who, according to local press reports is not sleeping well and lost his temper at some of his camp members for failing to wake him up on time for a training session. Coetzee stopped sparring 10 days before the fight and is keeping in shape by long distance sprinting and heavy bag punching.

Coetzee has said, "Win, lose or draw, I will have no self-reproach. No regrets because I did not make the most of my big chance in life. I have trained very, very hard and I am as ready as I'll ever be. I know that I will win, but I know that it's not going to be easy."

In contrast, Tate has appeared nonchalant and relaxed these last few days, spending free hours looking at films of fights of his hero, Joe Louis.

"He didn't take anything from anybody," Tate told a South African sportswriter.

The American's entourage is referred to as the "Hillbillies" by the South African press, because "they talk in a Tennessee accent that's a mystery even to the initiated," wrote one sportswriter. Tate comes from Knoxville, Tenn.

Between their training sessions, Tate and Coetzee have dipped into the golden till of endorsements. Coetzee posed with his favorite black cocker spaniel, Wendy, in a full page ad that recommended a certain dog food for a "balanced canine diet." And Tate has plugged watches, men's clothing and a brand of corn-fed chicken.