ATLANTIC CITY, N.J., JUNE 15 -- Michael Spinks proved again tonight he is a survivor in the ring who can find a way to win against the odds. In his greatest offensive performance, Spinks stopped Gerry Cooney at 2:51 of the fifth round, after twice knocking his 6-foot-7 opponent to the canvas.

Spinks put Cooney's shadowy boxing career into eclipse with two tremendous right uppercuts, prompting refereee Frank Cappuccino to stop the bout in what obviously was an act of mercy.

In raising his professional record to 31-0 with 21 knockouts, Spinks surprised the slightly favored Cooney by going on the attack in the fifth round after backpedaling and scoring with jabs and combinations through the first four rounds. Spinks hit Cooney virtually at will with lefts and rights to the head, capped by the two uppercuts that brought an end to the heavyweight nontitle fight before 15,732 in Convention Hall.

The only damage suffered by Spinks was significant; a head butt in the third round opened a cut above his right eye. Holding gauze to the wound after the fight, Spinks said the cut caused him to go on the attack in the fifth round.

"The cut made me a little more respectful -- I had to get on the go," he said. "I had to become more effective. I had to pep up the pace. I had to fight more."

Spinks was jubilant after a victory that eventually could earn him a shot at premier heavyweight Mike Tyson, if Spinks wants it. "I'm sure eventually somewhere along the line we'll have to fight," said Tyson, the World Boxing Council and World Boxing Association champion.

For the moment, Spinks was thinking only of his victory over Cooney. "Now the little guys all over the world can stand up and feel proud tonight," said Spinks, a reference to Cooney's 30-pound weight advantage.

Cooney was in no condition to meet the press with his career in shambles. He sent word through a spokesman that he was "disgusted" with his performance, and "never got his rhythm in the ring."

It was only the fourth heavyweight bout for Spinks, the former undisputed light-heavyweight champion, and his first nontitle bout in the weight class. He took the International Boxing Federation crown from Larry Holmes in his first heavyweight bout, but after two successful defenses he was stripped of the title when he signed to face Cooney instead of No. 1 challenger Tony Tucker.

For Cooney, the defeat had to mark the end of his career for all practical purposes. Fighting for only the fourth time in the five years since he lost to Holmes, Cooney was attempting to position himself for a title fight with Tyson.

But in the second major fight of his career, Cooney (28-2) again failed. Knocked out by Holmes in the 13th round in 1982, Cooney was even more embarrassed tonight as he was pummeled.

Spinks, at 6 feet 2 1/2, 208 3/4 pounds, fought a tactically brilliant fight, backpedaling in the early rounds but still scoring effectively with left jabs and occasional rights. After four rounds, the three judges had the fight even, with one favoring Cooney (39-37), one Spinks (39-37) counts, and the third judge scoring it 38-38.

It was a left that first hurt Cooney midway through the fifth round. But, overall, Spinks seemed to land his heaviest blows with the right hand, starting many of his significant combinations with right leads while Cooney apparently was watching for the left jab.

Cooney (238 pounds) landed the heaviest punches of the first round, when in the last minute he caught Spinks with a left uppercut and left hook combination. Cooney also landed a right as Spinks spent most of the round backpedaling and keeping his right hand high to protect against Cooney's hook.

Cooney hit Spinks hard with a left uppercut in the first 30 seconds of round two. Cooney continued to press the attack, scoring with a left to the midsection and a left to the head. Spinks landed a left jab to the face, and followed with three stiff jabs, bobbing Cooney's head. Spinks followed with a combination to Cooney's head, then two more stiff jabs. Spinks hit Cooney hard with a combination to the head ending with a hook that left Cooney staring at Spinks.

Spinks continued to pepper Cooney with good jabs in the first minute of round three. Spinks scored with a right and four consecutive lefts to the head. It was evident that Spinks could find the stationary target. Cooney countered with two strong lefts that backed up Spinks and sent him on the run.

Cooney hammered Spinks with a left to the ribs and two lefts to the head one minute into round four. Cooney pressed Spinks, who kept circling away from Cooney's left, but Cooney still managed to land several hard lefts to the head. That was Cooney's last hurrah.

Spinks switched tactics in the fifth, and landed lefts and rights to the head while moving forward. He backed Cooney to the ropes and scored with a hard left hook and a right. Spinks unleashed a barrage of lefts and rights to the head, dropping Cooney to the canvas. Cooney got up, and Spinks resumed the attack. Spinks continued to hit Cooney with lefts and rights to the head, again dropping him

Cooney managed to get to his feet and, though extremely dazed, continued. Again Spinks hammered with lefts and rights and, finally, when he landed the two right uppercuts, Cappuccino stepped between the two men and ended the fight.

"I'm a happy man," said Spinks. "You can hold your head high, buddy," he added, meaning Cooney. "You just didn't lose to anybody, I'll put it like that."

From the beginning, Spinks made no secret of his plan to exercise extreme caution against Cooney: strike when possible, but immediately try to leap back from harm's way.

This was the same scheme Spinks used in his three major fights. In those -- two against Holmes and one against Dwight Muhammad Qawi, formerly Dwight Braxton, for the light heavyweight title unification -- Spinks won close 15-round decisions by jabbing, landing occasional looping rights and moving.

Spinks made clear he was fighting for survival against Cooney. Going in, Spinks said he believed Cooney had "a big advantage" over him because of Cooney's weight and reach. But, he allowed, "I think the pressure's on him -- what type of fight will I present to him."

For his part, Cooney expressed more eagerness to fight than Spinks. Cooney had been criticized widely for staying out of the ring for long intervals after being stopped by Holmes in 1982. Since then, Cooney has fought only three times.

Cooney's numerous ailments and fight postponements tarnished his once-bright image as he was being brought along carefully for the showdown with Holmes. Cooney came into this fight trying to set himself up for a fight with Tyson.

Cooney had his best luck with fighters who came to him, and has said that he would prefer fighting Tyson to Spinks.