Will he or won't he? Will Marvelous Marvin Hagler choose to fight Sugar Ray Leonard, or will he opt for a rematch with Thomas Hearns? Hagler has been making it the most celebrated question since Hamlet's classic dilemma of some 400 years ago.

But it soon will be resolved. Hagler has selected Tuesday, in Las Vegas, as the day he will end the suspense. Will it be Leonard, once more unretired and panting to get in the ring with Hagler, or will it be Hearns? There have been no leaks.

That Hagler has been enjoying this guessing game is certain. It is his turn to tease and tantalize. No more waiting on the pleasure of Leonard, boxing's one-time Mr. Box Office, who used to call the shots. Now it's the turn of Hagler, undefeated in nine years and the only undisputed world title-holder in the game, who is top dog.

It is understandable that Hagler is savoring this switch in authority. For years, he groused at the rich paydays of Leonard, the welterweight champion, while he, the dominant middleweight, was fighting for funny money. A special envy of Hagler was the $27 million Leonard pulled down for only three fights, against Roberto Duran (twice) and Hearns.

Early in 1982, when Hagler wanted a shot at Leonard and the big money, Leonard's camp rebelled at his demand for equal pay. "Nobody should get as much as Leonard," said Mike Trainer, Leonard's attorney, "and Hagler's people should know that."

And then Leonard's man snapped off this zinger: "The biggest payday Hagler ever got was $1 million, and the promoter lost money on that fight." It was in this era of his discontent that Hagler, in his pout, threatened to retire, for lack of appreciation by the promoters and public.

On May 1, Leonard grandly declared his unretirement, with the specific aim of getting into the ring with Hagler. He has been left to cool his heels ever since, with no word from Marvelous Marvin. Leonard has been throwing a fit at the delay. "This doesn't make any sense," he said. Hagler has been unsympathetic. Perhaps because he has much to remember.

One day for Hagler to remember was Nov. 9, 1982, when he was invited to Baltimore along with a cast of other notables, for "A Night With Sugar Ray," a charity affair at which it was anticipated that Leonard would announce his decision to fight Hagler.

Hagler was seated at ringside when Leonard, looking down at him from inside the ropes, microphone in hand, declared: "A fight with this great man, this great champion, would be one of the geatest fights in history. Talk about money. Talk about Fort Knox . . ."

What Hagler next heard from a smiling Leonard was: "But unfortunately, it won't happen." Leonard announced he was retiring.

Hagler had come all the way from Brockton, Mass., only to be told there would be no fight with Leonard, no big payday, no nothing. Leonard's smile had been Chaucer's "smile with a dagger under its cloak." Hagler had been zapped.

So on Tuesday, Hagler will be making his own decision, with Leonard being left to wonder what it will be. The place he has chosen for the announcement is Caesars Palace, with Hagler's news conference upstaging the trumpeted boxing tripleheader of the night before, when promoter Bob Arum will show WBC super welterweight champion Hearns against Mark Medal, WBA featherweight champion Barry McGuigan against Stevie Cruz, and Roberto Duran against Robbie Sims in a middleweight bout.

The surprise will be if Hagler, who has his own zest for the big purse, prefers Hearns over Leonard. A warmed over Hagler-Hearns has none of the box office quality or marquee value of Hagler-Leonard. Hearns lasted not quite three rounds with Hagler last year.

Leonard has ventured that a Hagler-Leonard fight would fetch each of them a $15 million payday, The contrast: Hagler's pay was only $2.5 million when he fought Hearns last year.

It is also remembered that back in 1983, when Hagler defended his title against Wilford Scypion for $1.25 million, he moaned, "Here I am, a champion with three belts WBA, WBC, and The Ring magazine and there are guys with only one belt with a lot more money in the bank than I've got."

Leonard has said about the possibility that Hagler would choose Hearns as his opponent: "It makes no sense from a business standpoint or a history standpoint. Hagler has been getting bad advice."

That Hagler will, eventually, give the nod to Leonard is the expectation. Hagler-Leonard offers all the curiosity necessary for boffo box office.

Can Hagler reach a fighter who moves like Leonard, a man who also can snap off a punch against the sometimes-easy-to-hit Hagler? How much did nearly four years of retirement deplete Leonard's skills? Will Leonard's once-detached retina be a target, considering that in boxing, everything above the belt is fair territory? It could be a war in the making. Unless the unthinkable occurs, and Hagler says it's Hearns.