Few were surprised when heavyweight champion Larry Holmes finally vanquished Gerry Cooney in the 13th round of their World Boxing Council title bout Friday night. Holmes had been punishing the challenger with left-right combinations almost at will.

The surprise came almost an hour later, when the judges' score cards became public. All three had Holmes ahead, but on two cards the margin was so small it stunned veteran fight observers.

Sam Solomon, a Philadelphia trainer, simply shook his head in wonder when told of the scoring by judges Dave Moretti and Duane Ford. Promoter Don King said, "I was completely mystified by the scoring."

Moretti and Ford both had Holmes ahead by two points, 113-111. Both totals included debits of three points to Cooney, penalties assessed by referee Mills Lane for low blows the challenger landed.

Setting aside the penalty points, both scorers thus would have had Cooney ahead on merit through 12 rounds of the fight.

When Cooney, the 6-foot-6 challenger from Huntington, N.Y., finally arrived at a postfight press conference, it was hard to imagine how he could have been winning. He was leaning on the shoulder of his manager Dennis Rappaport and wore dark glasses to cover a battered and bruised left eye that Holmes had peppered for the last six rounds. He was a picture of dejection and defeat.

The fight was ended as Holmes pursued Cooney around the ring, punching him relentlessly after a straight right hand rendered Cooney defenseless. Referee Lane stepped in to stop the battering and was about to give Cooney a standing eight-count when the challenger's trainer, Victor Valle, jumped in and threw his arms around his fighter.

It was declared a technical disqualification at 2:52 of the 13th round.

The third judge, Jerry Roth, scored the fight 115-109 in Holmes' favor.

The judging proved of particular interest because both camps had argued over the selection of officials. Rappaport had requested out-of-state judges for the bout early in the week, on grounds Nevada judges might owe allegiance to King, who promotes Holmes' fights.

The Nevada Athletic Commission refused to go out of state for judges, but chose two men whose selection left King's assistant, Duke Durden, and the Holmes camp fuming. One was Moretti and the other was Herb Santos, who had little experience.

Holmes' camp protested to the World Boxing Commission, and WBC President Jose Sulaiman asked that Santos, at least, be replaced.

He was, in a highly unusual last-minute change. The commission named Roth to replace Santos and it was Roth who by most ringsiders' accounts produced the most realistic score card.

Durden, a former chairman of the Nevada Athletic Commission, said if he were still on the commission "and they scored a fight like that, I would recommend that they be pulled from the (judging) rotation." Added Durden, "Overall, they didn't have the three most competent officials to score the fight."

But the beauty of Holmes' victory was that it never needed the acquiescence of the judges. He knocked down the previously undefeated challenger in the second round with a sharp right hand, then fought cautiously and patiently until late in the fight, when Cooney grew tired.

In the ninth round Cooney landed a colossal low blow directly to the champion's groin that doubled Holmes over. Lane stepped in, walked Holmes to his corner and stopped the clock while the champion recuperated.

That and a later low blow in the round cost Cooney two points in the 10-point-must scoring system, and another below-the-belt punch in the 11th cost him the third point. None of the illegal blows seemed intentional; instead, they appeared to be outgrowths of Cooney's lurching, amateurish style.

But the low blows in the ninth had a secondary effect. When Holmes answered the bell for the 10th, it was with fire in his eyes. He attacked the taller fighter again and again with left-right combinations to the head, and the pattern was established that eventually ended the bout.

Cooney's left eye was cut and swollen and blood was evident on his nose and in his mouth. By the 13th Cooney's vaunted left hooks lacked power and he seemed unable to see the champion's straight right hands as they rained down on him.

The fight, for which each boxer is expected to earn as much as $10 million, was widely ballyhooed as a real-life sequel to the movie "Rocky," and attempts were made to create racial overtones, with Cooney in the role of the Great White Hope.

But afterward Holmes, triumphant for the 12th time in defense of the title he has held four years, said there were no hard feelings. "I shook Gerry Cooney's hand before the fight and I shook it after the fight."

He added, "I didn't fight this fight for blacks or whites or Spanish. I fought it for the people. I fought for myself."

And, he said, "I hope Gerry Cooney knows what I feel and who I am. On my part, what you (the media) wrote was a hype. It was too bad Gerry Cooney had people in his corner telling him different things."

Holmes celebrated his 40th professional victory against no defeats late into the night at a party at Caesars Palace hotel with his wife, Diane, who in three months is expected to give birth to their second child.

Meantime, Cooney was receiving stitches to close the wound in his left eyelid.