You would like Michael Spinks, younger and most accomplished brother of Leon, the former heavyweight champ who whipped Muhammad Ali in 1978, back when everybody said Ali was no longer Ali and Leon was just a goofy, gap-toothed kid from the ghetto who talked funny and couldn't keep out of trouble.

Michael grew up in that same St. Louis ghetto, a colossally doomed project called Pruitt-Igoe that was later razed or, as he puts it, "bombed out forever," when it became an ugly, crime-infested spike hammered in the heart of the city.

Yet another of the ghetto's progeny, Michael Spinks always dreamed big, though big in those days was best measured on the scale of human suffering. What he wanted was a simple means of transport, a way out. "Believe," he liked to say, "and anything can happen."

Now, in the dry heat and bright, unadoring light of this desert city, Michael Spinks is preparing to challenge Larry Holmes for his heavyweight title. The significance of the fight -- to be staged Saturday at 9 p.m. (EDT) in an outdoor arena at the Riviera Hotel and Casino and telecast on HBO -- is two-fold. First, Holmes is trying to equal the 49-0 record set by Rocky Marciano on Sept. 21, 1955. And attempting to deny him that mark is Spinks, who, at 29, hopes to become the first light heavyweight champ successfully to challenge the heavyweight boss in a title bout.

"One thing's already happened to me that everyone said wasn't possible," Spinks said. "I left, I left my hometown, and I always wanted to leave. I always said I didn't belong there. I'd say I know this is not right, I know there's a better place for me to live. And I still love the place, I love it. I just knew I couldn't and wouldn't live there."

He is gravely aware of the improbability of success. Over the past 64 years, six world light heavyweight champions have tried and failed, including Bob Foster, who fought both Ali and Joe Frazier, and Archie Moore, the last man to fight Marciano and only the second to knock him down. Moore, who now is working as a special assistant to Holmes, lost to Marciano in the ninth round.

"I feel the same identical way (those light heavyweights) felt," Spinks said. "I think I can do it, too . . . They didn't do it, I know. But still, it's the way they felt. And it's the way I feel right now. Anything's possible."

Although Spinks (27-0) is far and away the best light heavyweight around, he is giving up as much as 35 pounds to Holmes, who packs very little flab on his 6-foot, 3-inch frame. Spinks generally fights at 175, but this week he has refused to divulge his weight. His promoter, Butch Lewis, says he "ain't lettin' that information out because that's just something else Larry'll have to deal with."

Spinks said he wants "to keep it a surprise, I like surprises," and adds, "I've been eating so much I'm sick of eating."

Lewis says Spinks will enter the fight with "an extra layer of armor across his front" as a result of his intense, four-week training session in Louisiana with Mackie Shilstone, a New Orleans nutritionist and strength coach who played wide receiver for the Tulane football team in the early 1970s. Shilstone said his responsibility since first working with Spinks three years ago "was to get him at 175 pounds or below and the lowest body fat level possible with as much muscle as possible . . . Although he will be lighter than Larry Holmes, we're very close to Larry Holmes in muscle mass. I'm almost certain that Larry Holmes has much more body fat than Michael does."

Spinks has been training here for three weeks now and appears in superb condition. After working in the awful summer heat and humidity of Louisiana, Lewis said, Las Vegas "feels pretty good even at 105 degrees." While in New Orleans, Shilstone said he had Spinks going through an "unorthodox or revolutionary program that did not include road work. We did track work instead . . . Because each round lasts three minutes, we had Michael running 880s for conditioning, at about 2:46 for each one. That puts him 14 seconds shy of three minutes, the equivalent of one full round, then he would get a minute break, as he will during the fight . . . Right now, Michael's so strong that even I am impressed. He's learned that he's got tremendous explosiveness. And he's bigger than he was. You can see how the young lion has grown."

Spinks says fighting a big man is not that much different than fighting a man his size, because, he said, "pretty much the same thing can happen, though the effects may be a lot quicker." He said he does not expect Holmes to lean on him and wear him down early in the fight and will not even plan a strategy.

"It's really his fight," he said. "He's the big guy . . . He has everything to his advantage, including the most important thing, his weight."

Spinks tried but could not remember the last time he entered a fight as the underdog, but said he "felt like one every time I go into a fight. It's funny how people follow a winner, but everybody pulls for the underdog . . . Millions of people would love to see me win. It's weird how that works."

For some reason that he would not discuss, Spinks said he "really feels" for Holmes, and that "something makes me love him. But as a boxer, he's just another guy."

Spinks truly seems undaunted by the challenge. All his life, he said, he was "getting picked on by people bigger than me," including brother Leon, who once fought with him over a bologna sandwich and busted his cheek open with a curtain rod. He said if he wasn't fighting Leon, he was fighting because of Leon, and remembered a kid named Larry Brooks. As Spinks tells it, he and his girlfriend were walking down a stairwell in his building when Brooks "sees me, stops and slaps me across the face for no reason. I was about 14. 'This is for your brother,' the guy said. And he slapped me again, right in front of my girlfriend. Everything was for my brother. But I saw him again not long ago, I saw Larry Brooks."

Somebody asked Spinks what he told Brooks, and he said, "Before I could say anything he came up and congratulated me . . . He was bigger than me when we were kids. But he's a little guy now. I'm a lot taller than him."

After an afternoon workout, Spinks sipped on a cup of thirst-quencher and looked back on more of his days living in Pruitt-Igoe, which he once called "the land of terrible, a rough, rough place."

"Once I got jumped by this gang," he said. "They spotted me in a crowd for some reason, me and this guy named Gilbert Coleman. I said, 'Gilbert, we're being watched.' Then I told him to (move) on the count of three. Now, I couldn't run as fast as Gilbert, so I got caught. Everywhere I ran, there was a guy there waiting, waiting to hit me.

"They said, 'Come on, little Spinks. Come on,' and they hit me. They said, 'Are you Leon Spinks' brother?' And I said, 'Yeah.' And they hit me again.

"Later on, I'm sitting on these wooden blocks and I'm mad. I'm mad because I'm getting beat on for no reason at all and because the world isn't fair. Pretty soon, I see one of the members of this gang walking by. I said, 'You ain't gonna jump me by yourself, are you?' So he sends this guy to go get the rest of his gang. I told him I'd fight him but no wrestling. That was the rule. We'd stand there and box but no wrestling. So we walk out to this lot and next thing you know a gang of guys appears. I hit him with a jab and take off running, and I run in a complete circle. I run until I run into a fence and they start working me over. Then all of a sudden, out of nowhere, Leon comes and he's standing there. He tells them to stop it, but they keep punching me in the mouth. 'Get out of the way, big Spinks,' they said. 'Get out of here.'

"Man, I'll never forget that. I had on a Charlie Brown sweat shirt, you know the kind. Then this little guy came up with a switchblade. And he sent everybody away.

"But what happened, the following fall, one of those guys who jumped me and beat me was sitting right next to me in class . . . And that guy became one of my best friends. He had the greatest left jab you ever wanted to see; he could have been something. But it happened to him. He died, man. Robbing some place. Security guard shot him. His name was Louis Finch and he might have made it."

Spinks clenched his fist and waved it in front of his face, at no one in particular. "The way I see it," he said, "if I can come out of that, anything can happen."