SUGAR RAY Leonard is a piranha in blood water.

The old-timers praise him most as a finisher.

A finisher first hurts a man. Gets him dizzy.

Beats him on the head some more.

Puts him, the old-timers say, on Queer Street.

The man is helpless.

It is time to finish him.

"A time to love, and a time to hate," said Ecclesiastes.

"It's like I'm two different people," Leonard said. "I look at me on film and I see that vicious person. I don't recognize him. Something just clicks on in there."

When it is time to finish a man, Leonard clicks on.

In 27 fights, all of them victories, Leonard has knocked out 18 men.

He finishes them quickly. The welterweight champion is young, only 24. He is strong, a 147-pounder who will grow bigger. What he sees, he hits. He hits it before he knows he sees it.

A man is on Queer Street. Bewildered. Staggered by three punches, four, five.

His hands come down off the sides of his face.

He is against the ropes.

Time to finish him.

"Ray is the best finisher since Joe Louis," said Angelo Dundee, Leonard's manager.

Leonard comes into the ring wearing a smile.

Don't believe it.

The ring is a square jungle. No one smiles for real in there. In there, if nowhere else, Muhammad Ali was an honest man. Remember Ali in the 15th round against Joe Frazier the first time. Losing and on his back, Ali yet rose up to finish it, an honest man and brave, more warrior than jester.

Forget the megawatt smile.

It is not Leonard, the fighter.

It is Sugar Ray, the con man.

Harmless con. Fluff and dazzle. Tailored suits, the brass-knuckle array of golden rings, the elgantly thin chains holding the word "SUGAR" at his throat -- all of this is mere costumery, the haberdashery of a con man, not a fighter. No harm done. Maybe some grandmothers will buy a ticket to see the sweet young man play his game.

Forget the smile.

Against Roberto Duran, in the jungle, Leonard will forget the smile and bring the jab.

Leonard can do it. All clowned. In that first fight with Frazier, he clowned. He leaned over the top strand of the ring ropes and shouted to the customers, "Noooo contest." This was early in the fight. He soon shut up and began to jab.

As Ali's jab was the cornerstone of his game, a snake-lick of a punch that was both defensive and offensive, so is Leonard's jab.

With the jab, Leonard knocked down a man who at the time was a world welterweight champion. He so controlled Wilfred Benitez with the jab last November that Leonard was misled into believing he could end the fight at any time with a long right. Leonard wasted precious energy missing Benitez, a crafty fighter, with that right.

That won't happen against Duran.

Leonard learns.

Ali landed punches in bunches. Following the jab came a straight right, a hook and a right cross. Against Frazier, Ali done with his clowning, beat lumps into Frazier's face with dazzling combinations.

Leonard will do that to Duran. This fight is Leonard-Duran, and it is Ali-Frazier.

Ali and Frazier split $5 million in 1971. They were both undefeated, both under 30 years old. What that fight did at the box office, Leonard-Duran will exceed. There will be more than 70,000 people in Montreal's Olympic Stadium on Friday night. There are 1.5 million theater seats available for the closed circuit broadcast of the fight. It will be seen on home television in Europe, South America, Puerto Rico and the Orient. In Columbus, Ohio, in small parts of California, pay-TV subscribers will pay $10 to bring the fight into their living rooms. Leonard's purse likely will be $3 million -- with $8 million a possibility, depending on ticket sales -- and Duran will get $1.5 million, tax free.

The old-timers say Leonard-Duran is big.

They say it is up there with the second Louis-Schmeling fight. That one, old-timers will tell you, was War World II with gloves on.

Or they say it is Marciano-Walcott.

It is Ali-Frazier.

Here's the sweet con man with his charm.

Sugar Ray.

The con man with his jab.

With his finishing combinations.

He floats in the ring, a wrath appering as if from nowhere, there to finish you.

Sugar Ray, the piranha.

Leonard against Duran.

The angry Duran.

Relentlessly angry.

Ali beat lumps into Frazier's face. To see Frazier in the 13th round that night was to see a man climbing out of hell. And he kept coming. By actual count, Ali hit Frazier twice as often as Frazier hit him. Frazier's counted more. Finally he knocked Ali down, causing Ali's feet to rise above his head. Red tassles dangled from Ali's shoetops. Frazier won the fight.

Now comes Duran against Leonard. Leonard wears red tassles atop his boxing shoes. Duran's jab is good, if not great, while every other thing he throws is made of stone.

Leonard's people would have you doubt that. By knocking out 55 men as he won 69 of his 70 fights n a 13-year career that has marked him one of the game's greatest fighters ever, Duran has earned the nickname "manos de piedra." Hands of stone.

Pebbles, Leonard says. Pebbles that knocked out lightweights, not the 12-pound-heavier welterweights in Leonard's division. Ali said Frazier was too ugly to be in the ring with him. Leonard says Duran is just another fighter.

"Duran was king of the hill in the lightweights, but up here in the welterweights he's just another fighter," Leonard said. "I'm tired of all his talk. I don't want to beat Roberto Duran. I want to kill him."

Con man talk. Silly con man talk.

The question is: Who is Leonard trying to con? Duran or himself?

He didn't bother Duran, the one they call "El Diablo." The Devil. It isn't fair, that name. Outside the ring, Roberto Duran is a nice man. Inside, where it is legal to be less than a nice man, Duran is a rage incarnate.

"I hate Leonard," Duran said two weeks ago. Evil seemed a resident in his black-stone eyes. "He said he'd kill me. He was stupid, just shooting off his mouth. He was just talking, but when I say it, I mean it."

Leonard likes to stare at his opponents during prefight instructions. He stood forehead-to-forehead with Benitez.

"If he tries that with Roberto," said an old-timer, "Roberto will spit in his face. And his first punch of the fight will be below the belt."

Leonard has considered the possibility Duran will spit in his face. "Then there will be a fight before the fight," he said.

Con man's talk. It is to sell tickets. It is to get ready to go into the square jungle. Leonard is 24 and rising, Duran 29 and holding. They will be mighty combatants, as Ali and Frazier were, and then, once or twice more, they will fight again, it was so good.