Through no fault of his own, Sugar Ray Leonard's finest hour was tainted tonight by controversy.

Roberto Duran, the supposed epitome of the macho man, quit in the eighth round, saying he suffered a cramp in the fifth round that virtually paralyzed him. It prompted the question: Why did it take him 2 1/2 more round to decide he couldn't go on?

It was announced after the bout that the Louisiana State Athletic Commission was holding up Duran's purse pending a thorough medical examination.

Leonard jokingly called Duran's ailment "heartburn."

To a questioner who wondered if Leonard's punch to Duran's side in the final round was enough to make him surrender, Leonard replied, "If someone hit you in the body the way I hit him, you'd get cramps too."

Leonard said, "Duran quit of his own free will; don't try to put words in his mouth. It doesn't take away from the victory; I won fair and square."

What punch "paralyzed" Duran?

"All of them," Leonard said, attempting to shoot down Duran's contention that cramps spread to his arms and left him unable to continue.

Leonard had said he was going to "drive Duran crazy" and capitalize on his mistakes when he got angry, and that's just what happened.

Leonard destroyed Duran's mind with the most effective "psych" job seen since it was practiced by Ali, the master. Then Leonard took the Panamanian's heart away with a lightning series of punches reminiscent slickness in the 1976 Olympics, finishing up with a sickening punch to the side.

It was the seventh round that did the most damage, psychologically, when Leonard was fighting the fight he failed to fight in Montreal.

Leonard taunted the champion with his gloves down at his side, inviting punches as he wiggled his shoulders, wiggled his hips, mugged, theatrically wound up a windmill bolo punch before letting it go, and waving for Duran to come in and fight.

Duran forced a sickly grin, trying to imply he was not going to be taken in by Leonard's attempt to make him made. But he did get angry, to no avial. Leonard easily avoided his lunging punches and peppered him with spectacular punches of his own.

Leonard told interviewers, who were unwilling to believe that Duran could be beaten so handily, "They said he was going to knock me out. My friends back home bet against me. They said Ineeded a tune-up bout before a rematch with Duran."

The last remark was an allusion to former trainer Dave Jacobs, who was dismissed by Leonard after they differed about the necessity of a tune-up.

But the questions continued.Someone asked "Did you have any idea why Duran quit?"

"I don't know why he quit, but he did. I felt I surprised him with my style. He couldn't change his style. He wasn't able to catch me. He was a sportsman at the end. After he stopped the fight I walked over to him and he said he respected me. Why doesn't everyone else? He doesn't have any excuses."

Another interviewer mentioned that Leonard seemed to smile in self satisfaction at the end of the third round. Was that when Leonard knew he had Duran?

"I knew I had him when I entered the ring."

Richie Giachetti, Larry Holmes' manager, was near Duran's corner and he said the first report from Duran's handlers was that the Panamanian quit because "Ray wouldn't fight."

All sorts of rumors circulated in the crowd of about 40,000 in the Superdome. Jose Sulaiman, president of the WBC, first said Duran quit because he missed Leonard with a right-hand punch, a nerve went dead, and he couldn't move his arms after that. Later, Sulaiman said Duran suffered cramps from food he ate before the bout.

Giachetti heard Duran say, "I don't box no more . . . no more," before he announced that he was retiring.

Sig Rogich, WBC representative and head of the Nevada State Athletic Commission, reported Duran "got hit in the guts and the muscles in his arms would not move after that."

There was an announcement to deny a report that Duran was going to a hospital. It was said he was going to his hotel, instead, and would be examined later.

His manager, Carlos Eleta, a prominent industrialist in Panama, was visibly distressed about Duran's condition when he shepherded the boxer out of the group interview room.

Leonard was a 6 1/2 to 7 1/2 to 5 favorite over Duran in New York, a 6-5 favorite here, where there is a large concentration of Spanish speaking people.

Still, the rumors started when it was announced that Duran's purse was being held up.

After all, he won 72 of 73 bouts before tonight, with 55 knockouts.