What Friday night's championship fight needs is a certified, hateful villain, right out of an old-fashioned melodrama.

The trouble is, except perhaps in Washington, D.C., Roberto Duran has been one of the most popular boxers ever, from New York City to the Argentine.

Sugar Ray Leonard has been America's sweetheart since he graced the television screen from the 1976 Olympics here.

Until today, Duran's communication with the public for this bout has been stultified by having to go through the "laundering" of an interpreter.Duran mouthed some hoke about Leonard being a "clown" and so forth, but the animal vibrations of the man, his speech patterns and rhythms had lost almost everything in the translation.

He was being characterized as a "grump," but it was mostly because he was embarrassed by his language barrier.A promotional stunt ended that today when he appeared in a ring set up in the lobby of the Meridien Hotel, fight headquarters here, on his 29th birthday.

Duran made his statement with body language, from the moment he came out doing high kicks, tips of his toes reaching his fingertips outstretched over his head. So much for the back problem of two weeks ago. He did the "kazatska," the Russian dance requiring kick-outs from a squatting position.

In contrast to Leonard's workout before several hundred spectators at Paul Sauve sports center earlier, there was thousands watching from the ground floor and four balconies.

Duran was introduced as the "Killer from Panama" and a full-blast rendition of the theme music from the film "Rocky" caught up the fans in the emotion.

The former lightweight champion smiled and waved to the crowd and shouted his approval -- "Oui, oui, Montreal!"

To indicate how seriously he took this workout, the Panamanian made the sign of the cross before the first round. He stalked the tall, slender sparring partner who had a reach the image of Leonard's.

A right hand lead crashed on the jaw of the sparmate, Don Morgan, and knocked him into a sag on the ropes. The fans roared, in the round Duran scored a left hook to Morgan's head, simultaneously taking a right to the body, and Duran theatrically stepped back registering surprise to the crowd because Morgan did not go down.

Near the end of that round, he was pummeling Morgan so wildly that Duran's trainer abruptly halted the session and sent in a replacement, Ted White.

When White tried to tap-dance and jab his way from harm, Duran urged, with jaw jutted out, "Come on, come on, fight!"

The round over, Duran stunned the media by reaching through the ropes and shaking hands with ringside reporters.

He mugged for the television cameras while applause welled up in appreciation of his artistry as he danced laterally and did leaping squats while skipping without hitting the rope. He feigned fatigue in exaggerated slow motion and then came the big finish -- the lighting of sparklers on his birthday cake on the ring apron.

The people who had walked in off the street on extended lunch hours actually sang "Happy Birthday" to Duran.

He invited a select few to his hotel room and when asked to account for his bubbly expressions of good cheer, said, "I don't have to go all out against my sparring partners anymore, because I am in such good shape right now."

Trainer Freddie Brown said Duran weighed 148 this morning, a pound over the welterweight limit, and thus had that much to spare for loosening up the next couple of days.

"I'm only thinking of one thing," Duran said when asked for a prediction, "to win, by a knockout. I didn't come all the way to Montreal to be a clown . . . to do a lot of clowning (an allusion to what he calls Leonard's antics).

"Leonard can run all he wants, but he can't beat me by running."

Someone relayed a quotation of Leonard's today that the champion was going to beat the challenger at his own game, trading punches.

"I hope he tries," Duran said to his interpreter. "Don't let him be crazy. He talks so much he doesn't know what to say."

Leonard gets his shot at the noon-time crowd in the hotel lobby on Tuesday.

Leonard boxed for the first time in eight days, raising again the question of whether he had shed too much weight last week when he rested for a couple of days after being down to 144.

"I was down kind of low, to 143," Leonard acknowledged. "I got a little weak from training hard, and the pressure of a big fight like this takes off a few pounds.I put back some weight by eating steak. I was 151 this morning, so my weight's no problem."

He wore only a light cotton T-shirt and rayon trunks and threw a left hook so fast that sparring partner Mike James said he saw it coming but could not do anything about stopping it in time to prevent a knockdown.

Did he expect Duran to be as rough as when he knocked out Ken Buchanan for the lightweight title in a brawling exhibition by the challenger in 1972?

"No," Leonard said coyly, "he has much more polish now."