Undefeated heavyweight champion Larry Holmes, sent sprawling to the canvas by an overhand right by Renaldo Snipes in the seventh round, battled back in the 11th round tonight to score his 11th successful World Boxing Council title defense.

Before 12,000 vocal fans at Civic Arena, Holmes prefaced his technical knockout by staring out at the crowd and winking as the bell sounded for the 11th.

He went straight for his upstart challenger, measuring the Yonkers, N.Y., fighter with a right hand that missed cleanly. But he pursued Snipes into the center of the ring and tried the same tactic again. This time the right staggered Snipes, and Holmes followed him into the challenger's corner.

There, much the way he did to Leon Spinks five months ago, he pounded away mercilessly until referee Rudy Ortega stopped the fight at 1:05 of the round, declaring Holmes (213 1/4 pounds) the winner for the 39th straight time in his pro career.

Snipes (215 3/4), who lost for the first time in 23 pro bouts, reacted with horror, and stalked across the ring with his hands held high in the winner's pose. But it was all over: he had taken a thorough beating. "He was defenseless," Ortega said.

Members of the crowd, having rallied around the underdog challenger, began chanting obscenities and advancing on the ring. When Snipes and Holmes converged on television announcer Howard Cosell, Holmes' brother Jake got in a shouting match with the challenger and almost came to blows with Nick Rattenni, Snipes' manager.

A scuffle ensued, during which Snipes was cut on his left arm.

"He got cut by accident by a pair of scissors," said Rattenni. "Somebody bumped into somebody behind him. The person behind him was one of his handlers holding the scissors."

Dr. Frank Santora, the physician treating Snipes, said the challenger's injury was a "real deep laceration of the left forearm with a possible muscle cut about two inches deep."

Until the 11th, the highlight of this fight appeared to be Snipes' sudden, unexpected knockdown of the tall champion. Holmes had been in firm command through the first six rounds, although he had not managed to put down the challenger.

But early in the seventh Snipes, who had been given no chance by fight followers to overturn the champion, advanced, attempting two quick and harmless lefts and following with a lunging overhand right that sent Holmes flying. It was only the third time in his pro career that Holmes had been knocked down.

He wound up halfway across the ring in a neutral corner, groggy, but got up quickly and managed to survive the round.

Asked afterwards if he were worried at that point, Holmes said, "I wasn't hurt. I was more surprised. He hit me on the back of the head and I went down from it. I was aware of where I was." He said he had been hit harder in his career, most notably by Earnie Shavers.

But Holmes said it was a treacherous moment. "He almost pulled an upset," said the champion. "It was lucky I trained as hard as I did."

He said when he got Snipes in trouble in the 11th, "I didn't want the ref to stop it. I wanted to take him out."

Rattenni agreed, but for a different reason. "A championship fight should never be stopped until someone is down," he said. Rattenni noted that Snipes had come back from two knockdowns to beat Gerry Coetzee, and that he was "getting ready to do some damage" against Holmes.

Snipes was considered such a long shot for this fight that odds makers wouldn't offer a betting line. Holmes seemed totally confident in the days before the fight, and that confidence nearly cost him.

This bout was widely regarded as a tuneup for his scheduled match in March against Gerry Cooney. Holmes conceded that he was toying with Snipes early on, in an effort to draw him into a mistake, and that he was "practicing things, practicing my game for March." "He was a little stronger than I anticipated," said Holmes, explaining how the 25-year-old challenger had managed to take his best shots for 10 rounds.

And when Holmes hit the canvas in the seventh, imperiling an estimated $10 million payday for the Cooney fight, he said he guessed, "Don King (the promoter), Cooney and Caesars Palace all wet their pants." He said he was thinking only "of Larry Holmes getting out of the ring without being hurt."

The champion looked relaxed at a postfight press conference and had no visible signs of injury.

"I'm one bad dude," he said, "and I'll be even badder when it comes time for Cooney."

The victory marked the 10th time in 11 fights since Holmes won the title in 1978 that he has won a title defense by knockout.

It was the final fight in a long night of heavyweight battles that featured six of the top 10 WBC contenders.

Michael Dokes, 23, the fast-handed, undefeated No. 2 contender, had minor trouble with Baltimore's unranked George Chaplin before Chaplin tired in the last stages of their 10-rounder. Dokes won a unanimous decision.

So did sixth-ranked Randy (Tex) Cobb, who stood toe to toe with Bernardo Mercado through much of their 10-rounder, but was unable to finish off the ninth-ranked Colombian although Mercado spent much of the bout reeling around the ring, looking for a place to fall.

And 10th-ranked Jimmy Young, a venerable pro noted for his skill at defensive boxing, kept lumbering eighth-ranked Thomas (Franco) Thomas of West Virginia at bay well enough to win his fight by unanimous decision.