Sugar Ray Leonard said yesterday he would beat middleweight champion Marvin Hagler "by outboxing him," and that if the two meet it would be "the greatest fight in history."

All the buoyant Leonard needed, after an hour of sparring at the Sugar Ray Leonard Boxing Center in Palmer Park, Md., was Hagler himself -- but Hagler has not been heard from since before Leonard said Thursday that he would come out of retirement to fight the champion.

Hagler was said by a source yesterday to have ended his vacation. Hagler's manager, Pat Petronelli, said Friday that Hagler was in the Caribbean, but Petronelli has not been available for comment since then. Goody Petronelli, Hagler's co-manager, said last night that neither he nor his brother had yet been in touch with Hagler.

While waiting word, Leonard said more strongly than ever that he did not need any tuneup fights before meeting Hagler, a ferocious puncher who never has been stopped in his 62-2-2 career and has knocked out 52 opponents.

"He is the tuneup," Leonard said. "I don't want to go into the ring thinking I need a certain number of fights to fight a guy I know I can beat."

Leonard appeared to be thinking of winning a decision rather than attempting a knockout of Hagler, who has been described by opponents as relentless and almost impossible to slow up.

"I feel I can beat Hagler by outboxing him," Leonard said. "Mobility. Speed. A combination of things.

"Technically, I can outbox him," said Leonard, adding that Thomas Hearns made a mistake last year when he was knocked flat by Hagler after trying to slug it out with him. "All my fights have been strategic fights."

Dave Jacobs, Leonard's trainer until 1980, who was working yesterday with Leonard, added to the impression that Leonard would try to box Hagler cleverly and pile up points.

"It's going to be hard for Marvin to lay a glove on Ray Leonard," Jacobs said. "No way I can see Hagler beating Ray Leonard.

"His style is going to give Hagler lots of problems. My feeling is his boxing style can beat Hagler. He's a good boxer, good mover, good puncher.

"I just think Ray is too fast to get hit by Marvin -- and if he gets hit by Marvin, he'll never get hit solid. No way."

Leonard said September would be ideal for a Hagler fight, but a problem could be ongoing negotiations for a possible Hagler-Hearns rematch in November. Asked if he thought Hagler would prefer to fight him first, thus putting off Hearns, Leonard replied with a smile, "Who?"

Leonard's camp believes a Hagler-Hearns rematch would be far less of an attraction than Hagler-Leonard, in which each fighter might make as much as $10 million. What Leonard's people don't know is how far along the Hagler-Hearns negotiations are.

"I'd be surprised if Marvin isn't agreeable," said Leonard's adviser Michael Trainer. "It's just a question of when."

Meanwhile, Leonard's wife, Juanita, sounded as enthusiastic as Leonard's associates about her husband's possible return to the ring. "If Hagler did call and said, 'Let's fight in the next three months,' " she said, "he'd be ready."

While watching her husband spar, she said Leonard and Hagler "are good friends" and "call each other" and see each other at fights, and that on all these occasions they have discussed "what might have been, what could have been" had they fought. "This is probably a dream come true not only for Ray but Hagler as well," she said.

Indeed, Leonard said that recently, "he gave me the pleasure of coming to my restaurant, and we talked about what it would be like if we fought. Regardless of the outcome, we both mentioned the fact that it would be the greatest fight in history."

Since then, "I think he gave up on it. Now, it's a shocker to him."

The charged-up Leonard said that "four or five months ago I got on a scale -- it was a vanity thing -- and I was 168," and from that time he's been working seriously: five miles in the mornings, "two or three times a week in the gym," exercising, resting, "eating right." He now weighs 156, nine more than he's ever weighed in the ring but about the weight at which he would fight Hagler.

"I've seen a tremendous change in him the last three months," said Juanita Leonard. "A tremendous change. I guess you have to be in his shoes, a person of his caliber, to understand."

"People have said this is crazy, this is ludicrous," Leonard said, "but these people haven't had gloves on. They can't relate. . . . I respect their opinions. But they're not me. I am who I am.

"It's not money. It's not fame. I have nothing to do with either of these. It's just something I feel I can do."

"He appreciates people's concern," said Juanita Leonard. "Everybody thinks they know what's best for Ray. That's why I stepped back and let him make the decision. Win or lose, he knows what he wants."

She said that the detached retina of the left eye, for which Leonard was operated on in May 1982, was "the least of my concern" -- that he had been cleared by doctors following the surgery and before his comeback bout with Kevin Howard in February 1984, and that he has had regular checkups since.

As Leonard and Trainer before her, Juanita Leonard said her husband was "definitely not" coming back for money. "I don't spend that much," she said.

"That would be the last thing he'd get up there for. We haven't begun to spend what we have."

The reason for fighting Hagler, she said, is simply that "right now Hagler is the best out there. And Ray wants to be the best. He's always wanted to fight him."

To that end, Leonard worked hard yesterday. He spent several minutes intentionally absorbing body punches from a sparring partner, periodically springing out of his lowered-arms stance to pummel the opponent with lefts and rights. Leonard also dressed the part of his championship days, wearing a shiny red headgear and glossy black hightop shoes.

He said a major difference in a comeback to fight Hagler as opposed to his comeback to fight little-known Howard, when he was knocked down before winning, was "motivation, with a capital M" -- and this was the reason his wife was encouraging him. "She's more confident this time. It's the motivation factor. Kevin Howard just wasn't the challenge that I needed."

Similarly, Leonard said he believed that Hagler "needs" him, too. The fight "will create immortality for him if he should be successful. I think he deserves to be ranked among the greatest boxers, but for himself, his own satisfaction, it's me that's going to give it to him."

Leonard, who will be 30 on May 17, insisted that the long layoff -- one fight since February 1982 -- would not affect him. "I never went by boxing rules, traditional ways. I've always done things my way."

All he wanted was a call from Hagler or his managers saying they were interested. Said Juanita Leonard: "As Petronelli said, he Hagler would fight King Kong if the price was right. How could he turn down little ol' Ray Leonard?" Harris Wins Bout Associated Press

CEDAR RAPIDS, Iowa, May 5 -- Washington, D.C., boxers James Harris (106 pounds), Darin Rivers (147) and Little J, Jowers (heavyweight) won on decisions today in Golden Gloves preliminary round bouts.

Washington's Kelvin Daly (119) and Lorenzo Wright (165) lost by decisions and Dale Anthony Reid lost on a first-round knockout.