A moment of truth emerged after tonight's fight. When Roberto Duran, the new welterweight champion, was asked, "Were you surprised that Ray Leonard slugged with you?"

"He had no choice; he had to," Duran replied through an interpreter.

Corroborative justification for that assertion came from the most surprising source, Leonard, when he came to the microphone.

"I proved I could take the big punch," Leonard said, mindful of that question having been raised so often before tonight. "I had to," Leonard acknowledged. "I had no alternative."

Duran screamed at Leonard the moment the final bell rang, gesticulated wildly with both hands, and charged after the former World Boxing Council titleholder before being restrained. He also screamed at television interviewer Dr. Ferdie Pacheco, who speaks Spanish and translated.

Pacheco said, "Duran is mad because he wanted Leonard to "fight" for 15 rounds. Duran quoted Leonard as saying, "I'm a boxer."

Duran seemed frustrated at not being able to speak English in the interview room. "A lot of people thought I was just a heavy puncher, but I am also a boxer," he said.

After the third round, Freddie Brown, one of Duran's seconds, shouted at the referee, Carlos Padilla. Asked during the interviews what he said, Brown explained, "I told him to watch how much Roberto was making Ray miss. I told him to stop Leonard from holding Roberto and to let Roberto fight."

Duran was asked what made the difference in winning the fight and he patted his heart. "I won with my heart -- and my head," Duran was quoted as saying.

Was he implying that Leonard didn't have heart?

"No," the Panamanian said. "If he didn't have heart, he would be dead."

Asked what he screamed to Leonard at the end of the bout, Duran said, "I told him, 'I beat you . . . I beat you.'"

The bout was a masterpiece and a rematch would seem a natural, but when Duran was asked about giving Leonard a return bout, he was evasive "I don't know; my manager will decide." Manager Carlos Eleta was sitting beside Duran, but offered no comment.

But Leonard was similarly evasive when he was asked if he wanted a rematch.

"Time will tell," he said.

Wilfred Benitez, who plans to marry Leonard's sister, said here the other day that he was going to get a shot at the WBC title he lost to Leonard on Sept. 23.

That was before tonight's upset victory by Duran. After the bout, one of the most elated well-wishers greeting Duran was Don King, who has promoted most of the Panamanian's bouts.

Leonard displayed a cut on the inside of his right eyebrow, which he said he incurred during an accidental bumping of heads. "He dazed me with an overhand right in the second round, but I was able to shake it off because I was in such great condition," Leonard said.

Despite saying he felt confident he was winning before the final bell, Duran was trying to impress the judges by making a show of getting up on his toes and jabbing theatrically, something he had not done during most of the bout. He had just taken a heavy punch from Leonard and registered a mocking smile to suggest that it didn't really hurt him.

Despite all the years that trainer Ray Arceln, 81, has been in this sort of thing, he tried his hand at influencing the judges and crowd by raising Duran's hand in victory before the decision was announced.

Duran let his happiness all hang out once the decision was announced, as if greatly relieved. He hugged manager Eleta while promoter King beamed and put a protective arm his newly enhanced attraction.

Duran wore a badge of battle in the interview room, a lump under his left eye, as he sought nourishment from an orange. For want of something better to say, he shouted, "Bonjour, bonjour, Montreal; oui, oui."

Emotions ran high in a mob scene as security broke down. A Canadian tried to conduct the interview, as planned, in English, French, then Spanish. It got out of hand as Benitez shouted from the audience at Duran in Spanish. Duran's entourage threatened Benitez and security men charged after frustraterd newsmen.

The 29-year-old product of the barrio fights in Panama sat calmly through it all, except for an occasional menacing glance in Benitez's general direction.

Duran showed his age at times, his punches lost some sting late in the bout, as did Leonard's. But if it was a story of Paradise Lost for multimillionaire Leonard, it was Paradise Regained for Duran, who had been the cock of the walk before as the best lightweight of his time.