While white South Africans gloomily reassessed the defeat Saturday of their boxing idol Gerrie Coetzee by John Tate, black communities joyously celebrated the black American's World Boxing Association heavyweight championship.

"I thought Soweto was burning again," said black boxing promoter Joe Gumede, who described how people were dancing in the streets, beating tins and creating a bigger fuss "than New Ear's" in the all-black township of Soweto outside Johannesburg after the result of the fight in Pretoria was announced.

Shebeens, the illegal bars in Soweto, announced a 5-cent "John Tate victory discount" on all drinks for next week, the newspapers reported. Tate will visit Soweto, a community of 1.5 million, on Monday.

Meanwhile, the defeated South African, who had gone into the ring with the hopes of his fellow whites on his shoulders, said today, "I'm sorry, South Africa. I tried my very best. I'm in no way trying to make excuses, I've been beaten by a better man. Tate is a good fighter and he'll make this even clearer in future fights."

In the Tate camp what ought to happen next is obvious: a match with World Boxing Council champion Larry Holmes -- and discussion centers around when.

"I feel like I'm the champion in some respects but I don't guess I would really feel in my mind I'm the true champion till I have both titles, the WBC and WBA," the happy Tate told a press conference today.

Tate's promoter, Top Rank's Bob Arum of New York, repeated today his undisguised challenges to Holmes and his promoter, Don King.

"The guy that has the other half of the title is not stupid," Arum said, "and his people aren't stupid. And they know if they go in against this team, they don't have a chance.

"It's got to be a question of when the most money is available to pay off Holmes for the other part of his title. It's as simple as that . . . And it may very well be that it's going to take until September or October (1980) when the television money is at its greatest.

"But if the money was available now, by that I mean February, then fine, or if Holmes feels differently and will fight for less money, then by all means (the fight can be earlier than next September)," Arum said.

Asked about his statements that he is in favor of a winner's promoter taking all, Arum had an opportunity to cast a jobe at his main rival, King:

"Absolutely, winner taker all, that just doubles the profit. But that includes King's 30 percent managerial share of Larry Holmes . . . You got to say it like it is."

"John's going to be the champion for 10 years and he's got to make as much money in that time as possible," Arum said.

The Americal promoter said, however, he is sure Tate would easily beat Holmes, because "of his ability, stamina and discipline and because he has the best corner in boxing today."

For Arum, the Tate team adds up to "the Dallas Cowboys of the boxing business."

"You saw a revolution in boxing (last night) -- a corner coming in with a game plan from start to finish," Arun said of the bout that drew 89,000 to a heavily secured Rugby stadium.

"Tate's "game plan" was to avoid exerting himself in the early rounds and let Coetzee tire himself out, then come on strong, which the American did from the fifth round on.

Tate said today he thought he could have done 25 rounds "real easy."

"Gerrie has a tendency when he's in there, he likes to talk to you and there was some times I really wanted to open up. But I thought why chance it, if you're winning a fight why change and do something else?

"Every round that went by, in my mind I was thinking that I'd put on a little bit more pressure and about the 13th round Coetzee was (still) saying something of this nature: I'll get you in the next round.' And I said, 'Hey,' you gonna run out of rounds pretty soon, ain't ya?"

Tate said he would be "more than glad to fight Coetzee again."

Tate said Teofilo Stephensen, the Cuban amateur champion who beat Tate in the Montreal Olympics in 1976, was "one man I want to get off my list (off future opponents)."

But Aram said he thought it would not be possible to arrange a match with the Cuban until at least after the Olympics in Moscow, and possible not even then.

He related how he had had "extensive" negotiations with the Cubans to set a Muhammad Ali fight there but it was not feasible because the Cubans, and Ali as well, were asking too much money for the match.

For now, Tate is quite happy. "I got what I came over for," he said.

Before the match, in answer to American civil rights groups who opposed the bout, Tate said: "I get paid to fight. Jesse Jackson ( a U.S. civil rights leader) gets paid to talk. He has his job, I have my job."