To driving music heavy with the artillery booms of the drums he loves, Roberto Duran came to war against Sugar Ray Leonard. Thousands waved little flags of Panama on wooden sticks, waving them in time to the music's beat, and at 10:41 p.m. the other night, Duran bounded quickly through the ring ropes. His handlers unfurled a 15-foot long flag of Quebec in blatant appeal to his Gallic cousins here, and Duran hopped into a rapid burst of shadow boxing that took him in fast little circles.

Ray Arcel, his trainer, stopped Duran. Wait, he said. There will be time, he said. The time is later. The night will be long. And Duran stopped the fit of nervous work, for now to the disco beat of his own theme song, "Hey, Sugar Ray," here came the welterweight champion, Sugar Ray Leonard, the man who said he didn't want only to beat Duran but to kill him.

Leonard came into the ring as a gunfighter. There was a calculated deliberateness to his gait, subtle strut, the gunfighter's signature. Slowly he spread his arms to the hostile crowd, a crowd that earlier had booed even his picture on the giant telescreen in Olympic Stadium. This was not the Clint Eastwood looking for someone to shoot.

And right then, at that very moment, we should have known this was not Ray Leonard's night. The moment before the fight was Duran's. He came as himself. For the next hour of war, he was himself, fighting true to the values that have made him a fearsome and respected champion for nearly a decade. But Ray Leonard gave away part of himself that night, perhaps gave it away in arrogance, perhaps in awe of Duran, and a Leonard with a part missing was no match for a Duran whole.

Leonard did not move in this fight that was judged so close he would have won had two judges scored only one round for the champion instead of the challenger. If never an Ali floating in mesmerizing circles for 15 rounds, Leonard yet is an active fighter capable of evasion and pursuit. Just a day before the fight, Angelo Dundee, presumably the commanding voice in Leonard's corner, said his man would confound Duran by moving to the right consistently.

"That'll be my theme song, 'a little white light, and move to the right,'" Dundee said. The idea was that the bullish Duran charges straight ahead and would find no Leonard waiting there; instead Leonard would fetch Duran a hook to the ear. "Move to the right," Dundee said.

It never happened. For 15 rounds, Duran kept Leonard pinned on the ropes. Where an Ali, at 220 pounds, was strong enough to throw aside anyone who would force him against the ropes, Leonard could not budge Duran. Duran was always in his chest, reducing the 20-foot square ring to a speck of canvas big enough for two little men.

"Ray thought he could outstrong Duran," Dundee said four hours after the fight. Clearly, the commanding voice in the corner is Leonard's. He chose to stand in one place against a fighter whose single goal in the ring is to immobilize his opponent. "Give Duran credit," Dundee said.

Ray Arcel said Leonard made a grievous mistake when the bout was signed. He never should have said that about killing Duran. Had he said that to Duran on the street, Arcel said, Leonard would not have lived to see the next moment. Duran would carry those words into the ring, Arcel said. And Duran's trainer, Freddie Brown said, "When Leonard said that, you know what he looked like? Scared is what he looked like."

Duran is 29. He won the lightweight championship eight years ago in his second fight in the United States. His career since was marked by indifference. He loved to eat. He hated to train. The combination drove him from the lightweight limit of 135 pounds to 165 between fights. The only man to beat him, Esteban DeJesus, paid for it with two brutal beatings in rematches.

Duran the dark. If sometimes indifferent between fights, he always was evil in the ring. He is a cholo, a Panmanian of Spanish and Indian descent. The Indian in him produces a smoldering countenance that is residence to stone-black eyes of chilling intensity. His hair is raven black. Wet with sweat and corner water, the hair flops madly as Duran bulls forward. A dark and scraggly beard completes the sinister look of a man who won the lightweight championship when the champion couldn't continue in the 14th round -- having been hit below the belt, after the bell, by Duran.

Men have run from Roberto Duran.

"This is a very determined fighter," said Arcel, who put an emphasis on the word "determined" to let a listener know it was a euphemism. "Determined" fighters will do anything to hurt an opponent. They will take any punishment to deal punishment of their own. As much as Duran hit Leonard the other night, and it was terrible to comprehend, that much Leonard hit Duran. But he kept coming, Duran did, and a man at ringside, astonished, said, "Duran's the kind of guy you couldn't kill with 12 bullets."

Determined. At 29, anything but indifferent to the rich American who said he wanted to kill him, Duran punished himself through 10 weeks of training, the longest camp of his life, and turned his little linebacker's body into the fighting machine it is meant to be.

Men have run from Roberto Duran.

"Don't forget," Arcel said, "this is a street kid. He lived in the streets of a ghetto worse than any you can imagine. He had no home, he grew up sleeping in the street. The very depths of poverty. He had to steal to eat and he had to fight to keep what he stole. All these things gave Roberto a rage to live."

Ray Leonard did not run.

It was foolish to stand and fight. Leonard should have moved. He came in a gunfighter, but he let the other guy choose the weapons. What Leonard did not do was run, for on this night he stood up to a man of rage and skill and great heart, giving as much as he got. We could argue the unanimous decision, though Leonard said the better man won and he had no excuses.

Notes from the 15th round of the title fight . . .

"L doesn't want to touch gloves with D. . . . L big rt. . . . L on ropes, D charging more. . . . D never stops. . . . D taps own chin, clowning, mocking L, dances away . . . . after bell, D leaps 3' in air, hits L on back, Arcel pulls him away. . . . D going crazy, screams at L, it's over but D going crazy."

When the decision was announced, Sugar Ray Leonard, a loser for the first time in 28 fights, let his head fall onto the shoulder of his brother, Kenny.

And Roberto Duran, that raven's hair shining, hugged Carlos Eleta, his manager. It was 20 years ago that Eleta caught a street urchin stealing mangoes from his farm near Panama City. The boy's name was Roberto Duran. m