Aaron Pryor should have been whooping it up, but this morning he was just tired and worried.

Twelve hours earlier he had battered Alexis Arguello to retain his World Boxing Association junior welterweight title. It was Pryor's biggest fight ever and, he said, his roughest.

This morning he was worried about Arguello, who had slumped to the canvas bloody and unconscious and failed to respond to his handlers for long minutes after the referee stopped the bout at 1:06 of the 14th round. And Pryor's camp was concerned about accusations that its fighter used foreign substances during the bout.

Pryor went this morning to Jackson Memorial Hospital to see Arguello, but he said the World Boxing Council lightweight champion from Nicaragua was not there. Pryor was concerned because "I tried to go over to him after (the knockout), but he didn't seem to recognize me for five or 10 minutes."

Arguello's manager, Bill Miller, said his fighter spent the night at home under observation by a doctor and when he woke this morning "his mental reflexes were clear and he had all his facilities." He'd suffered a concussion and a severe cut over his left eye. The knockout was sudden.

Shortly after the bout, Pryor answered questions and appeared unhurt. But today his face was lumpy, his body sore and his voice a whisper. "I never took harder shots to the body," said the champion.

Pryor said he had stomach trouble before the fight and when Arguello saw how effective body punches were, he concentrated on them. "With a fighter like that, if you show a weakness he'll get to it," said Pryor.

The stomach trouble also was cited for Pryor's use of a special mix of liquids during the fight. Pryor's trainer said the mix was simply Perrier and tap water, a combination he said helped guard against a recurrence of diarrhea suffered earlier.

But Arguello's manager, Miller, said he had filed a protest with the WBA and the Miami Boxing Commission claiming Pryor used foreign substances during the fight and failed to take a urine test afterward.

Miller told reporters the fact that Pryor took Arguello's hardest punches and came back strong made him suspicious. Pryor's trainer, Panama Lewis, was overheard calling for the special mix over television microphones and Gene Marks, a member of the Miami commission, said some of the liquid spilled on him and had a strange taste and odor.

"I don't know what it was," said Marks, "but it wasn't water." Only water is permitted in a corner.

Miller said he would call for a rematch and Pryor said he would welcome one.

First, Pryor said he would probably seek a title defense against Ray Mancini, the WBA lightweight champion. (This was before the ill-fated Mancini-Kim fight yesterday.)

If Pryor proved anything in his sixth successful title defense and 32nd straight professional victory, it was his ability to take a punch. He has not proven over the years to be a hard man to send to the canvas.

"Alex hit him with some good rights," said Arguello's trainer, Eddie Futch. "He'd stop in his tracks or even back up, but four or five seconds later he was back in." Pryor showed that resiliency throughout the fight. "He came out each time just like it was the first round. Even after he lost the 13th round he came back fresh," said Futch.

Futch said he did not expect the devastating loss to end Arguello's career at age 30. "It was more exhausting than anything else," said Futch. And Miller said Arguello was "in no way contemplating retirement."

Arguello was seeking his fourth title in four weight divisions, something that has never been done in boxing.

It wasn't until the 13th round, Pryor said, that he began to feel he was getting to the lightweight champion. "I was hitting him a little more flush. I felt in my hands that he was hurt."

The next round Pryor swarmed out, seemingly fresh, and within 45 seconds had administered the straight right hand that sent Arguello reeling. He pursued Arguello against the ropes and pounded away at will until referee Stanley Christodoulou stepped in to stop the fight.