When the Marvelous one arrived at Caesars Palace Thursday afternoon, a nightclub singer dressed up as emperor Julius himself read from a scroll in a big Roman voice. A barmaid named Erma lifted her red velvet pillow and gave the middleweight champ the key to his suite, and another woman, this one wearing a bejeweled evening gown and a gold cobra headdress, did her best to look like a ripe but unaffected Cleopatra, queen of the Nile.

As is his way, the baldheaded man pulled up in a white stretch limo, accompanied by his managers, Pat and Goody Petronelli. After ascending the red-carpeted stairs, Marvelous Marvin Hagler waved to the crowd, said a few words and put himself back in jail, back where he could wrestle the assorted demons of his trade, hide from every last sweetness, watch the little red message light on his phone blink, talk to his own unsettling image in the mirror and brood.

Hagler (61-2-2, 51 knockouts) defends his undisputed crown Monday at 11:15 p.m. EST against John (The Beast) Mugabi before a live crowd of about 15,000 and a closed-circuit, pay-per-view television audience. Also featured on the card, World Boxing Council super welterweight champion Thomas Hearns (40-2) challenges James Shuler (22-0) for the North American Boxing Federation middleweight title.

Less than a year ago, Hagler and Hearns met here in the most brutal collision in recent boxing history, won by Hagler in the third round. Of that battle, Hearns said, "I gave it all I had. But the man has a head like a piece of steel. You can't keep hitting on that thing hoping it'll break."

In making his 12th defense since winning the title almost six years ago, Hagler, 31, faces a man who has won all 26 of his professional bouts by knockout. Mugabi, a 25-year-old Ugandan with a stinging right hand, repeatedly has said, "I will nuke 'im out," when asked of his chances against Hagler.

Never one to blush or experience goose flesh in the face of a challenge, Hagler ground his teeth, chewed on a few choice adjectives and replied, "Mugabi, you're taking nothing away from me . . . You're making me mad making those brash remarks. You'd better be nice to me."

Looking to break Carlos Monzon's middleweight record of 14 consecutive winning title defenses, Hagler continues to fight the finest contenders in the 160-pound division. In the days leading up to a fight, he is as hard, caustic and unobliging as an old bird. When seen moving like a shadow through the casino or at a news conference, he hides behind sunglasses and rarely smiles or even moves his lips. He wears his famous meanness like a crown, and sometimes seems to be on the verge of a long, angry howl. Regarded by almost everyone as the best fighter in the world, Hagler still approaches every bout as if he were some unfortunate challenger working for bread money.

"All those middleweights are looking at me, they want what I got," he said. "Let me tell you something, it's not easy. It's a tough job to have. So if you do get it, you have to work very hard to maintain it and stay on top. That means 24 hours a day and not just inside the ring but also on the outside.

"I realize Mugabi's got a dream. He's out there, eyeing what I got -- all the jewelry, all the clothes. It takes hard work, they're not easy to come by. It took me a long time to put food on the table and be at nice places and sit around with nice, dignitary people. It took a long time for me to talk like this, too."

For his work, Hagler will receive $2.5 million. Mugabi will earn $800,000. In what fight people like to call the "co-main event," Hearns will make about $1 million, four times as much as Shuler. If both Hagler and Hearns win Monday night, promoter Bob Arum of Top Rank Inc. hopes to stage a rematch of the celebrated April 15, 1985 fight sometime later this year.

Hagler said he would fight anybody if the money was right. "The only way I can put it," he said, "nobody's taking nothing away from me because I've worked so very long, so very hard. I waited years for Muhammad Ali to step over and the sugar darling, Sugar Ray Leonard, to give me the opportunity to prove that I'm the worthy champion of the people."

Hearns, 27, said he hopes to retire from boxing within the next year, after winning two more titles and becoming the first fighter in history to take four division crowns. If he can beat Hagler in the late summer or early fall, he said, he wants to fight for the light heavyweight championship, win it and then retire and train some of his teammates in the Kronk Gym of Detroit. But one cannot help but wonder how seriously wounded Hearns was against Hagler. All this week, he seemed so relaxed, so jovial, not at all like the fighter who once spoke in a deviant whisper, whose eyes almost turned yellow at the mere mention of his opponent's name. How much did the Hagler fight take out of Tommy Hearns?

"I should have no problems with James Shuler," Hearns said.

Shuler countered that he is "not intimidated . . . I got the hatred. I'm hating everybody right now. I say let's go and get it over with."