It is coming up fight night again in Las Vegas, with the curiosity to be ended and one important question to be answered:

When he faces Michael Spinks for the heavyweight title Saturday night, can Larry Holmes possibly involve himself again in as dumb and witless a performance as last time, when he let a blown-up light heavyweight dictate the tune of the fight and expose him as a confused, inefficient and weary old champion?

Last time, in September, Holmes went into the ring as a putative shoo-in, an 8-to-1 favorite, fighting on history's side, which had amply documented that no light heavyweight ever could lick a reigning heavweight champion. So much for ample documentation. All three judges voted Spinks the winner.

A strong reluctance to believe that it can't happen again is seen in the 8-to-5 odds solidly favoring Holmes in this rematch. The action in the betting shops has favored Holmes consistently, unlike last year's wavering odds on the Marvin Hagler-Thomas Hearns fight here. That was when Bob Martin, the premier betting authority, said: "They go to bed at night thinking Hearns and wake up in the morning thinking Hagler."

What they're betting is that Holmes can't fumble it away as badly as he did last September, when he could have handled Spinks' flitting style, and never exploited his 21-pound weight advantage. He couldn't get to Spinks' body where the challenger would be most vulnerable. This time he vows to take the fight to Spinks and get rough with him.

For this one, Holmes, now 36, is more than edgy. He has been snarling for weeks, in contrast to the easy mien of Spinks, now the new champion. Fight folks used to say that irritability was a sure sign a fighter was ready to turn tiger. But Holmes has been wallowing in his distemper to an alarming degree.

He has been calling Spinks and his manager awful names, and he's been saying the Nevada judges who voted against him last time were drunk, and worse. He had to apologize for that lest the Nevada commission cancel his license.

But there is nobody to crack down on Holmes when he keeps saying newspaper writers who don't like him are drunk, too, and that they tell lies about him. The other day he ordered his henchmen to eject bodily a New York writer, Dick Young of the New York Post, from a workout. Then he threatened not to attend the traditional pre-fight press conference, and didn't.

Even the mild-spoken Spinks said: "Looks like he's mad at the world."

Holmes' handlers like to say that one of the troubles last time was that, mentally, Holmes was fighting the late Rocky Marciano, not Spinks. So caught up was he in the passion of equaling Marciano's 49-0 and gaining the glory he craved, he overlooked Spinks, they say. Spinks had other ideas: "I didn't get in there to be 49 on his list."

The wonder is that two guys with such an impressive collective record, 76 fights without a defeat, could enact such a clunker last time. It was a 15-round bore, with Spinks mostly defensive, and Holmes plainly inept. The only suspense was the wait after the final bell to see if the judges had enough guts to give Spinks the fight he won, such as it was.

Spinks demonstrated quickly that he was without fear in facing Holmes. What he did was to fight a discreet fight, if not an aggressive one, moving, circling and keeping Holmes at a distance, and darting when necessary. He did score enough points to win. He was a survivor who didn't have to survive much, thanks to Holmes' inaction. He stuck to his game plan and got the desired results, the decision.

Holmes was the oddly reluctant fighter, a Ferdinand bull of heavyweights, who cared only to smell the battle, not get too close to it. His performance will be remembered mostly for the strong right hand he kept cocked all night in a sinister "I'll destroy you" gesture, and that he rarely put two punches together.

He set a mileage record for stalking a rival without pulling the trigger. Also, he chose to fight Spinks on the outside, which was Spinks' game. When he did try to close with Spinks, not very frequently, he couldn't find him.

In the last round, when Holmes might have pulled it out, he just stood there, as if relying on the judges to give him a gift of the verdict, as other judges had done in some of Holmes' past fights, on the cockeyed theory that a champion still standing is still a champion. He got spoiled.