Gerry Cooney's instant knockout of Ken Norton may have the gratifying result of knocking some sense into Joe Frazier's head. Only an hour before Cooney used 54 seconds to put Norton to sleep, Smokin' Joe was blowing smoke a mile high. Unbelievably, Joe Frazier was talking of a comeback. He was, sorry to say, serious.

"I'm leaning toward it," said Frazier, who hasn't fought in five years. "It's according to what goes on here tonight."

Once as ferociously elegant a fighter as you ever feared to see, Frazier went out on his shield June 15, 1976. That night in Uniondale, N.Y., George Foreman demolished Frazier in five rounds.

All we've seen of kindly ol' Joe since has been in those light beer commercials where he threatens to punish us with his singing voice. Now as manager of his son, unbeaten heavyweight Marvis Frazier, the old warrior is working out daily in the ring. And at age 37, with Muhammad Ali his elder, with Ken Norton probably as old, Joe Frazier is talking foolishly.

Two days ago he said, "With all the money they're throwing around now, I'd like to get some to boogey with."

For $850,000 Ken Norton took 54 seconds of cruel punishment. Hurt by a series of rights to the body and lefts to the jaw, Norton was helpless the last 10 seconds, unconscious but hung out to dry on the ropes, unable to fall to earth because his seat was caught on a ring rope.

It is Cooney's job to keep firing. He did. In the half-moment of indecision while referee Tony Perez decided to stop the fight, Cooney delivered five more bombs to Norton's face. For six minutes afterward, Norton sat on the canvas, unconscious half that time.

The state's ringside doctor, Edwin Campbell, said Norton was fine after three minutes. The doctor shined a light into the fighter's eyes. He put an ice pack on Norton's neck. He asked him questions.

"I asked him where he was and he said, 'Madison Square Garden, in the ring,'" the doctor said. "I asked him what round it was and he said, 'First.' I asked him to subtract three from 97. He answered fine. He is neurologically negative right now. He recovered rapidly."

And Joe Frazier, 37, wants that?

"My daughters and wife are coming to the point where they believe I can do it," Frazier said moments after his son's fourth victory. He sat in a dressing room at Madison Square Garden, just down the hall from the door that an hour later would come ajar to reveal Ken Norton flat on his back on a table.

"My sons know I can do it because they see me in the ring, trading punches every day," said Frazier, who an hour later would see Ken Norton never so much as touch Gerry Cooney. "My ladies are learning."

"What," someone wanted to know, "is the objection by your ladies?" The guy asking the question hoped to hear from Joe something that made sense, something that said someone realizes a man five years from the ring, a man grossly overweight (232, Frazier said), a man too old by far -- had the ladies said it was a good way to get hurt?

"They don't want to lose a good thing," he said, laughing.

Some newspapermen who have known Frazier for years believe the comeback talk was done at the request of the Garden, which dearly needed hype to sell tickets for the Cooney-Norton mismatch. With Cooney guaranteed $1 million -- that $18,518 a second -- the Garden's gate of $777,121 from 9,436 patrons is less than half the nut for the production.

Other people believe Frazier is serious, sort of. They think he can be induced into training, as he was three years ago for Kallie Knoetze before a bout with hepatitis convinced him to go on the road with his singing group, "The Knockouts." Once in training, these people believe, Frazier will realize the impossibility of it all.

Maybe. Ken Norton didn't.

Norton never had a chance, not from the day this fight was signed. At 6 feet 6 and 225 pounds, Cooney is a strongman. Norton hates strongmen. At the sight of a big fellow with a powerful punch, Norton soon falls into a swoon. George Foreman needed one round, Earnie Shavers needed one round and now Gerry Cooney needed one.

Cooney is legitimate. He moves forward well enough. He throws heavy punches in tight little arcs. Now 25-0 with 21 knockouts, he has a championship date this fall with Mike Weaver, the anonymous half-owner of the title. After knocking over the musclebound Weaver, Cooney will go against the other champion, Larry Holmes.

That will be a fight. Of Cooney's victims, only Norton has been ranked in the top 20 when he fought them. And Norton is a hollow shell of the young mediocrity who went 0-4 against fighters who were champions. But Holmes is a genuine fighter complete with dancing feet and a perpetual motion jab, who will test Cooney's ring sense as well as stamina and will.

Norton entered the ring tonight to no applause. Nothing. He climbed through the ropes to silence. No one cared. He says he is 35, but estimates of his true age run to 42. The body still is beautiful, rock hard, but it is empty now.

"I was going to apply pressure the last half of the round," Norton would say 20 minutes after he woke up. "By backing up, that was my mistake."

Sing a sad song, old man, sing a song of might have been.

It was 10:30 at night, and Ken Norton shrugged aside a guy wanting an autograph. A red lump had risen on the bridge of his nose. Another lump stood watch at the corner of his left eye. He tottered slowly down a hallway, his manager holding his elbow, then went behind a door about 50 feet from the room where, an hour before, Joe Frazier had said he might fight again.

"It would take me six weeks to get ready," Frazier said.

Who would he want to fight?

"Pull one out of a hat," the old man said defiantly.