When Gerrie Coetzee was 7, his father had to bribe him with 50 cents to put on boxing gloves and try some sparring in their neighborhood amateur boxing club.

Saturday, Coetzee, now 24, will get the largest purse ever paid to a South African boxer ($360,000) when he steps into a Pretoria ring against American John Tate to make South Africa's first stab at winning the World Boxing Association heavyweight title.

Coetzee's try for the title will have a significance far beyond the ordinary sporting aspirations of white South Africans. For this beleaguered minority, which considers itself the unjustified target of international double standards that ostracize it from sporting events in protest against the country's domestic race policies, Coetzee's title attempt represents a chance at a national vindication.

Through him the white South Africans can perhaps show the world that the isolation imposed upon their athletes, who have been excluded from the Olympics for 19 years, does not keep them from being as good as the rest of the world's best. And the fact that coveted sports titles makes their sports isolation more than a little porous in their eyes.

Some people believe Coetzee will be fighting for his fellow Afrikaners, the whites of Dutch descent who dominate the government.

Coetzee, however, sees himself in a slightly different role. "I feel I am fighting for everybody, black and white," he said, adding that he didn't like being referred to as "the great white hope" because "what really makes me happy is for black, brown and white people to accept me as their fighter."

Coetzee told newsmen today that if he won the world title he would use it as a platform to promote full equality in sports. "I will have many things to say and I will suprise a lot of people," he said, explaining that his stand on his country's discriminatory policies is that "people should be treated on merit and not on race or color."

These views, plus Coetzee's soft-spoken, clean cut image, will not hurt South Africa's case for a reversal of its isolation in international sports, something the government here is undoubtedly aware of and something that worries foes of apartheid who maintain that South Africa's whole political system must change before any meaningful equality can exist in sports or any other sphere of life.

One of Coetzee's heroes is Muhammad Ali whom he met in Las Vegas when Ali first fought Leon Spinks. "When he lost, I nearly cried," Coetzee said, disclosing that three weeks ago in a long-distance telephone call Ali gave Coetzee advice on how to beat Tate -- which Coetzee refused to divulge until after Saturday's bout.

Unlike his opponent, whose slick American-run operation includes a sparring ring under a tent hung with promotional advertisements, Coetzee works out in the gym of a neighborhood fire station in the working-class suburb of Bedfordview on the way to Johannesburg's airport.

Much of the local prefight hype has been devoted to publicity about the mild-mannered 220-pound boxer's "bionic hand." After Coetzee broke both his hands defending his South African heavyweight title in 1976, he had an operation in which the bones were scraped and fused into the form of a loose fist, that according to one doctor "could punch a hole in a brick wall."

The press debate has centered on how this fist will fare against chunky Tate and whether or not it gives Coetzee an unfair advantage over the American.

Apprehension about hurting his right hand got the Coetzee camp into trouble with South African boxing authorities last year after press reports disclosed Coetzee had worn a plastic shield to protect his fist under his glove in a fight. Coetzee admitted he wore the shield that he had fashioned with his dental technician's training from the plastic coating of a milk bottle.

The provincial boxing authorities suspended Coetzee and three members of his camp, including his trainer-father "Flip", Coetzee, for six months. The national boxing organization reduced the penalty to three months on appeal.

Gerhardus Coetzee (pronounced coat-zee-ah) is the product of a background in which boxing is a family affair. Two uncles were professional boxers; his father and two brothers have all been active amateurs. He grew up in the working-class town of Boksburg where his father, a motor mechanic, ran a local amateur boxing club. Coetzee overcame the complications of asthma and made up for a shy, retiring personality in the boxing ring, winning a provincial level bantamweight title at age 13. He left junior high school to get his dental technician's training.

In 1974 he turned professional, stacking up 22 wins, 12 by knockout, no losses and about $450,000 in purses and endorsements up to now, according to his manager, Hal Tucker. He became South African heavyweight champion in 1976 after defeating Mike Schutte.

Coetzee's big break came when he signed on with American promoter Bob Arum who pitched the South African from international obscurity into the limelight by matching him with Leon Spinks in an elimination fight in Monte Carlo June 24. Spinks was defeated by three right hooks in the first round. cCoetzee's contract with Arum runs through at least three title defenses if he wins Saturday, Arum said.

Coetzee already has found out what fame means. After beating Spinks he had to erect a brick wall around his home because he awoke one morning at 3 o'clock to find some over-enthusiastic fans in his bedroom. Real estate advertisements for homes in Boksburg plug the advantage of "living near Gerrie Coetzee."

Coetzee is known for his calculated, "scientific" style of boxing.He never has been floored in his professional career and his adept defense is facilitated by asile, speedy footwork as well as an ability to hit well with both hands.

Because he has not lost a fight since 1973, South Africans have an almost fanatical expectation that he will beat if not knock out Tate on Saturday.

"Thats worrying me," he admitted today, revealing that he is steering himself psychologically to go the full 15 rounds with Tate so he will not be shaken if he fails to put Tate away early.

"Tate will beat any boxer without a punch. But I see myself as a boxer with a punch. It's going to be a classical fight," Coetzee predicted.