Pervis Ellison attempted to hide his braces, but the smile glittered nonetheless, for Louisville's freshman center was the improbable hero of this national basketball championship.

His lay-in of senior guard Jeff Hall's air ball and his two free throws with 27 seconds to go that helped defeat Duke, 72-69, tonight were not the acts of a freshman. They were the accomplishments of a much older player, surely not this knock-kneed 18-year-old with buck teeth.

Oblivious to the bedlam around him, Ellison rose from the lane with 38 seconds to go to pick off Hall's floater and lay it gently back in the basket to give Louisville a 68-65 lead. Then he strode to the foul line a few seconds later and made two shots for a 70-65 margin that was insurmountable.

Which was to say nothing of his overall performance, which included a game-high 25 points. Which is why they call him "Never Nervous Pervis" at Louisville.

"That's Pervis," forward Tony Kimbro said. "He never gets excited."

It was not until Ellison came down off his victory podium and worked his way back to the locker room that his retiring ways came out again.

"I guess I was just taller than a lot of the guys out there," he said, stubbing his sneaker against the floor.

Ellison, who lives in Savannah, Ga., is a shy sort who tends to hide his braces with his hands. But underneath the bashfulness is a reserve of confidence: he was not recruited as a sure first-year starter, but quickly made himself one.

"I didn't know how he would turn out," Louisville Coach Denny Crum said. "We didn't promise him he would start. But he moved right in there. He's played that way for us all year, and he's going to get better in all kinds of ways."

That Ellison's points came exclusively from the inside was partly a result of his movement down low. He has sharp knees and elbows, but he also is graceful and promises to become more graceful as he puts on weight.

"We knew Ellison could get inside," forward Mark McSwain said. "We knew that was the way to win. There's not too much you can do about him when he gets it down low."

But Ellison also benefited from the attention Duke's back court was paying to Louisville guards Milt Wagner and Hall. Johnny Dawkins' and Tommy Amaker's efforts to chase them out to the perimeter left the Blue Devils' foul-riddled front court vulnerable. Jay Bilas was fronting Ellison, leaving no weakside help to come from behind.

"The guards were playing so tight, it let me get inside more," he said.

But that did not explain his last shot, the short leaping lay-in from the lane. Hall's shot was badly off the mark, but Ellison was right there for the decisive play.

"That was a pass," Hall said with a laugh. "As soon as I let it go I knew it was nowhere close. The other guys protected me by crashing the boards. I was very fortunate."

The play was a set one that originally had been called during Louisville's timeout with 48 seconds to go. The shot was supposed to go to either of the guards, Hall or Wagner.

"Coach called the timeout, and we discussed the play and said we'd try to get the ball to Jeff or Milt," Ellison said. "Jeff took the shot and I thought I was the only one that jumped. I didn't see anybody around me. I just layed it in."

According to Hall, what may have been more impressive were the free throws.

"He just plays great under pressure," Hall said. "The two crucial free throws in the national championship game, I don't think most freshmen could do that."

Louisville was widely thought to have taken a height advantage into the game at center. But that was supposed to be nullified by the experience of Duke's Bilas and Mark Alarie. Instead, the freshman showed the better ability to play with foul trouble, as well as equal savvy around the basket.

Alarie, for one, was not prepared for Ellison's performance. "I thought he made some great athletic moves," he said. "That did suprise me. He is a great offensive player."

Ellison's scoring made up for the horrid play of some upperclassmen Wagner and Billy Thompson.

"It was just one of those bad nights for me," Wagner said. "I couldn't get those things going. Pervis has been doing that all year."

Said Amaker: "He's probably the best freshman in the country."

That, apparently, is an understatement.

The game ended in an ugly manner when, as time ran out, Jeff Hall collided with Danny Ferry near the foul line after Hall had stolen the final inbounds pass. Hall wheeled on Ferry, hit him with the ball and then started for him. He was restrained by officials and spectators who rushed the court.

Ferry attempted to shake Hall's hand, but Hall refused. Later, Hall downplayed the incident. "He about broke my neck," Hall said, holding an ice pack behind his head.