For 13 rounds it was as even as a title fight is likely to be. But suddenly it was the time Aaron Pryor has been predicting all week: "Hawk Time," when he would swoop down on defenseless Alexis Arguello.

At 1:06 of the 14th round in their World Boxing Association junior welterweight title fight tonight, champion Pryor caught Arguello with a straight right that staggered the challenger. Then he pursued Arguello onto the ropes and launched a series of blows that had the lightweight champion out on his feet.

Arguello suffered a severe concussion, a broken nose and a cut near his left eye. He was rushed to a hospital for treatment, according to ring physician Marshall Abel.

Referee Stanley Christodoulou stepped in after six unanswered blows from the swarming Pryor and halted the bout, declaring Pryor the winner by technical knockout.

"Arguello's neck muscles went slack," said Christodoulou. The fighter fell to the canvas and stayed there for several minutes before lurching to his feet. He then had to take to a chair to avoid falling again.

"He was defenseless," said Christodoulou. And there was no doubt about it.

Arguello's manager, Dr. Eduardo Roman, said: "He never collapsed. We kept him down. He just didn't want to see anyone."

It was a sudden and surprising change of circumstance for Arguello, who in the previous round had landed two sharp rights and seemed to be handling the fight well. Neither fighter was knocked down until the deciding round, and two of the scorers had Pryor ahead while the third had Arguello in the lead.

The scoring was close: judge Ove Ovesson and Christodoulou had Pryor leading the fight, 127-124, when it was stopped. Judge Ken Morita had Arguello ahead, 127-125.

Arguello wept as he left the Orange Bowl after the fight.

"He's sorry for what happened. He's psychologically down," said Roman.

"Hold your head up high, Alexis," fans shouted to Arguello as he walked toward the parking lot.

Neither fighter dominated, though each managed to hurt the other several times.

But in the final round Pryor came out as fresh as if he were only halfway through the bout. He danced around Arguello, who continued to work from midring, essentially flatfooted. With a startling suddenness, Pryor landed the right lead that sent Arguello reeling toward his corner. The Orange Bowl crowd of 23,800 leaped to its feet.

Pryor followed Arguello to the ropes and landed at least six unanswered blows to his head before the fight was stoppped.

The loss ruined Arguello's bid to become the first boxer to hold titles in four weight classes. It was his fifth loss in 81 fights, but does not affect his standing as World Boxing Council lightweight champion, since he moved up a weight class for this challenge.

The victory seemed certain to assure Pryor, undefeated in 32 professional fights and six title defenses, of much more respect than he has previously been given as a champion.

Pryor said afterward that he felt in control all the way, but recognized the likely proximity of the scoring. "My corner wasn't so sure," he said.

Pryor's face was unmarked after 14 rounds with a man he said was "a great champion."

"It was an education for me," said Pryor. "This was learning to fight consistently for 15 rounds, even though it only went 14."

Pryor, who now has won 30 of his 32 fights by knockout, had never been forced to go more than 12 rounds before.

He said Arguello showed him that "some guys have a heart just as big as I do. He weathered the tornado" when Pryor swarmed out after him early, "and he started picking me apart in the middle rounds like I knew he would.

"Then I stormed him again and that's when I got him."

Indeed, that was the scenario as it appeared from ringside. It was Pryor who will get credit as the better boxer after this bout, though his reputation is as an undisciplined slugger.

He kept his cool in the middle rounds, even when Arguello caught him with two stunning rights at the end of the 11th and Pryor's trainer, Panama Lewis, raced out as the bell sounded to rescue his fighter with smelling salts.

The middle rounds were a case of Arguello loading up for his stiff rights while Pryor contented himself with three- and four-punch combinations. It was hard to tell who was getting the better of it.

At the end, though, there was no doubt. Arguello was led out by his handlers, his face a bruised and bandaged mess. Pryor answered questions with his wife Theresa and entourage at his side.

The two rights Arguello landed in the 11th "stunned me," Pryor said. "I felt his power, but he never caught me with one punch that made me think it was over."

The blow that turned the fight was a right lead that caught Arguello flush on the chin, said Pryor. After that, it was simply hot pursuit after the staggering lightweight.

There was no objection, even from about 2,000 fans who had flown in from Arguello's native Nicaragua, to the decision of halting the fight. Before the fight, the Nicaraguans led the crowd in singing their national anthem.

Pryor said the helplessness of Arguello at the end worried him. "I didn't want to hurt nobody," said Pryor, who in the past has seemed unconcerned about his opponents.

Pryor earned $1.6 million for this defense. Arguello got $1.5 million. It was the biggest payday for either.