ATLANTIC CITY, N.J. -- Larry Holmes had just won round three by hitting Mike Tyson with two hard rights to the head later followed by a sneaky uppercut, and now in round four the old codger was up on his toes dancing, yet flicking six straight serpent-tongued jabs into Tyson's startled face. This wasn't the way it was supposed to be. Young Tyson, after backing up Holmes and winning the first two rounds, was now getting a boxing lesson, with the flow of the fight suddenly changed.

And then, just as suddenly, Holmes' 38 years tattled on him, as did those 21 months of ring rust in retirement.

When the still ebullient Tyson returned to the attack, hostile as ever with two-thirds of the round gone, Holmes appeared spent, making no move to stay out of harm's way. Through Holmes' gloves ripped a Tyson left hook, and then the old champion was axed by the second part of the combo, a vicious right cross. Holmes was down, first down, and two to go.

Other knockdowns everybody now knew would simply be a matter of time, and there came two more, the last occurring five seconds before the round's end. For Tyson it was, in knockout terms, a finish most elegant. He had terminated his man, the one he had in trouble, in textbook style with few misses. Always it was a whistling right that was the force.

So conclusive was the final knockdown, occurring moments after Holmes, a plucky old champ, had waved off a referee who asked him if he wanted to quit that there was the threat that the fight had ended in a boxing tragedy. Holmes was down on the canvas, spread-eagled on his back, so inert that doctors leaped into the ring, first-aid minded. But when referee Joe Cortes was able to pry from Holmes the mouthpiece that was gagging him, good news was signaled by his cornermen.

The time has come to update the book on Tyson. If the undisputed title he claims is still a bit flawed what with Michael Spinks, the two-time conqueror of Holmes, still out there, Tyson nevertheless is the strongest, the most destructive, the most exciting heavyweight extant. His biceps resemble beachballs. His muscle is not only visible but he puts his strength to incessant use, intends to have his way in every fight, is a physical culture nut and outconditions everybody.

Those right hands, and an occasional left, with which he brought down Holmes would have felled anybody who didn't get out of the way. He was frustrated somewhat when old pro Holmes easily tied him up inside with the cute moves learned in his 19 years in the ring, but Holmes learned it was impossible to keep the lid on Tyson forever.

Never were prefight boasts more idle than those of Holmes, who had specified how he would deal with the upstart Tyson: "He's a face fighter {meaning he has no lateral moves}. He's made for me. Anybody who comes forward runs into my power." Tyson, scorning any subversive tactics like a feint, simply ran through Holmes' power and destroyed him.

Tyson's record, 33-0, is looking much better now. His earlier fights were faulted for the caliber of his opponents, and in total he has been beating as inferior an array of available stiffs as could be corraled by his managers. But on Friday night his resume added some character when he stopped Holmes. If need be, factor in Holmes' 38 years and long retirement, but in his 15 years in professional boxing, his 50 previous bouts, nobody else ever did it to Larry Holmes. Tyson was an exciting innovator.

Holmes had denied repeatedly it was the $3.1 million guarantee for the bout that brought him out of retirement. He insisted that his purpose was vindication and winning the title "they stole from me in Las Vegas," that pride was his great motivation. However, he did not always seem sincere about that, as when just before the fight he told a TV interviewer, "Anyway, if Tyson beats up on me and my head gets bloody I'll just go home and put a $3 million ice pack on my eye." He was saying he knew where and how to find comfort.