homas Hearns, who lost his welterweight championship a little more than a year ago to Sugar Ray Leonard, today won a 15-round majority decision to take the World Boxing Council super welterweight (154-pound) title from champion Wilfred Benitez.

And in the main preliminary to this title bout before about 15,000 in the Superdome, WBC super bantamweight champion Wilfredo Gomez retained his title with a 14th-round technical knockout over Lupe Pintor. Pintor fought valiantly before he was knocked down twice in the 14th and referee Arthur Mercante stopped the bout for the 122-pound crown.

In the main event, the tall, rangy Hearns knocked Benitez to the canvas with a sharp right hand in the fifth round and staggered him again in the sixth, but Benitez was saved by the bell.

Benitez rallied and grew more aggressive as the fight wore on. But in the end only one judge, Lou Filippo, had the score even; the other two had Hearns well ahead. Tony Castellano had it 144-139 Hearns, Dick Young scored it 146-136.

The two fighters, who had shown no affection for each other during final preparations for this title showdown, stared at each other menacingly before the bout but embraced with mutual respect afterward. Benitez smiled and seemed unsurprised by the decision.

Hearns had never before gone 15 rounds. His longest effort had been 14 in losing to Sugar Ray Leonard.

Benitez's face was marked and puffy from Hearns' left jabs. Early in the fight he had dodged the taller man's quick blows, but as it wore on and he becamed more aggressive, lunging after Hearns, he took more punishment.

In the fifth round Hearns came out dancing, jabbing away as he exercised his eight-inch reach advantage. Near Benitez's corner Hearns threw a straight, short right hand that caught the champion flush on the chin and sent him flying across mid-ring.

Benitez's glove touched the canvas as he struggled to keep balance, and Hearns lunged after him to deliver more blows. But referee Octavio Meyran, seeing the glove touch down, stepped in and delivered a standing eight-count.

Benitez, who had been playing it cagey up to that point, came out strongly in the sixth, mixing it up with the slugger from Michigan who had 32 knockouts in his previous 36 pro fights.

With three seconds left in the round Hearns caught Benitez with another right and the champion fell against the ropes. After the bell sounded he staggered to his corner, narrowly escaping a second knockdown.

But the fight was far from over. Benitez, in his third defense of the title he won from Maurice Hope in May, 1981, came back to hold his own for the remainder of the fight. He seemed to throw caution to the wind, wading in against the taller Hearns and connecting with good punches throughout the remaining rounds.

With 15 seconds to go in the ninth round, he caught Hearns backpedaling and landed a long left jab. Hearns, off balance, sprawled flat on his back in the middle of the ring and though the blow was not a damaging one, it was ruled a knockdown by Meyran.

Nor was it easy for Hearns the rest of the way. But he landed enough punches against the bobbing, weaving, feinting and lunging Bentiez to score the win.

"Benitez said he could beat me and Ray (Leonard) on the same night," Hearns exulted afterward, "but he better wake up. That ain't so. I was a boxer tonight, using the left hand, working it and getting my right through."

Hearns said he hurt his right hand at one point on Benitez's head and saved it the rest of the night, concentrating on the left jab. He said neither Benitez's knockdown of him or his of Benitez was a solid one. "He stepped on my shoes and I just tripped" in the ninth, he said. "I really didn't knock him down either. I hit him but I think he was well off balance."

Benitez's record fell to 41-2-1. Hearns, the new champion, is 35-1. Both had lost previously only to the newly retired Leonard, who was at ringside doing commentary for a television outlet.

In the preliminary for the World Boxing Council super bantamweight title, Gomez battled the game Pintor through 13 rounds and threw everything he had without apparent effect.

Pintor, the bantamweight champion who was moving up a weight class for this title shot, actually appeared to be doing more damage and Gomez' face was swelled and bruised. But throughout the fight Gomez landed hard left-right combinations and eventually they paid off.

He caught the challenger with such a combination in the 14th and Pintor went sprawling for the eight-count. Gomez raced back in and delivered another flurry of blows. Pintor went down and Mercante stopped the fight.

Gomez, though still on his feet, was lifted by his seconds and carried to his corner twice in the fight after the bell sounded to end particularly vicious rounds. "My corner saved me," he said afterward through an interpreter. "The guy took everything I could give him. I didn't think I'd win by a knockout. I'm grateful to get out of the ring."

His face was a mass of bruises. The left eye was nearly swollen shut. He said of the bruising, "My career may be in jeopardy," because of the facial beating.

Gomez scored his 18th successful defense of the title he won in 1977. His record now is 38-1-1. Pintor, who retains his bantamweight title, fell to 49-6-1.

Hearns has said he hopes to win four titles before he retires. He now has won the welterweight and super welterweight. Next, he said, would be to challenge Marvin Hagler for the middleweight title, "but I'm not going to think about that baldheaded man for awhile."