There's supposed to be no event in sports so electric as a world heavyweight title fight, but tonight when champion Larry Holmes pummeled Randall (Tex) Cobb for 15 rounds, there was barely a spark in the air.

Holmes' 13th successful defense of the title he's held since 1978 was neither pretty nor exciting. The one-sided brawl was played out before a smattering of 15,000-odd people in the cavernous Astrodome, and their occasional cheers for the home-state fighter, Cobb, sounded hollow. A national television audience watched as well.

They watched the uninterrupted pounding of the clumsy, overmatched Cobb, whose strength is in his ability to take a punch. Tonight he took a lifetime's share as Holmes won 14 rounds and tied one on two judges' cards and won 13, lost one and tied one on the third score sheet. Two judges scored it 150-135 Holmes, the third had it 149-136. All three had the 15th round even.

Cobb, a rough-hewn Texas wit, said afterward through a face purple with bruises, "I'd like to say Larry Holmes is one of the most uncooperative individuals I've ever worked with. He has little or no compassion."

In fact Holmes, the 33-year-old undefeated World Boxing Council champion, showed respect for the outclassed challenger, hugging him after the final bell had marked only the second time he'd failed to knock out his opponent in a title defense.

Holmes even seemed to ease off a little in the final round after manhandling the 234-pound Cobb in the ninth through 14th.

In the 15th round of this mauling Holmes eased the pressure, as if recognizing that he would never knock Cobb off his feet. That is the history of the unpracticed challenger, who in 23 pro fights--20 victories--has never been knocked out.

Cobb, 28, vowed before this mismatch that "when the smoke clears I'll be standing," and he was.

For his part, Holmes said he was glad of it and was worried for awhile that he might seriously injure Cobb, who never hurt the champion.

"I'm glad I didn't," said Holmes, "because boxing took so much with the death of (South Korean lightweight Duk-Koo) Kim" earlier this month.

Holmes said that after a fighter takes as much punishment as Cobb did in the early rounds, the danger of injury in a late-round knockout is great. It concerned him, he said, but he continued to punish Cobb up until the last three minutes.

Holmes, who won his 41st pro fight without a defeat, afterward launched into a diatribe about the need for safety reforms in boxing.

"If I fight again it will be mandatory that my opponent have a complete physical exam before I sign to fight," Holmes said. He said boxers need to unite on the issue of safety because "divided we fall, together we stand."

Together he and Cobb stood through it all, and when it was over the bruised and sullied challenger said, "I'll be back. I'm just learning. I feel like I just started tonight.

"I learned a lot," Cobb said, then added with a laugh, "not about moving my head, I admit. But I'll get that, too."

And he said that he didn't feel he lost, "I just ran out of time. If we stayed out there all night I'm sure one of us would have passed out."

It would have to have been Cobb, who was on the verge of having his head torn off on several occasions. His plan had been to wade in against the more experienced, jabbing champion. He waded all right, but Holmes hammered him with long left jabs followed by smashing right hands, and when Cobb got off a punch or two Holmes retorted with counterpunches that landed with thundering reports.

Holmes, who weighed 217 for the fight, about five pounds more than he had for the Gerry Cooney bout in June, earned $1.6 million for the defense, according to promoter Don King. Cobb earned $500,000.

Holmes' comment about the physical exams he would demand "if" he fought again sparked a storm of inquiries about the possibility of his retiring, but he said he still has the desire to fight and will continue until that desire burns out. He would not say who he intends to face next.

Presumably, it will be someone who brings the electricity back to a heavyweight title fight.

In the featured preliminary, Greg Page successfully defended his U.S. Boxing Association heavyweight crown with an eighth-round knockout of James (Quick) Tillis.

Tillis had sent the champion to the canvas in the second round with a sharp right-left combination for the only other knockdown, and he peppered Page with blows to keep the fight even through six rounds.

But in the seventh, Page, the fourth-ranked contender for the World Boxing Council title, began pummeling Tillis with rights that had the challenger grasping for the ropes to steady himself when the round ended.

At the start of the eighth Tillis, ranked No. 9 by the WBC, still appeared groggy. Page pursued him, connecting with a long right hand that staggered the challenger.

With Tillis backpedaling toward the ropes, Page faked a left hand and loosed a long right that started around his waistband and wound up on Tillis' chin. The blow lifted Tillis off his feet and knocked him out.