"Tommy Scates is sort of like a volcano. You're always waiting for it to erupt."

That was Georgetown Coach John Thompson describing his 6-foot-11, 245-pound senior center today after Mount Scates, as he is known on the Hilltop, destroyed Penn's basketball team with the force of an active Vesuvius.

On a day when star Georgetown forward Craig Shelton fouled out with almost seven minutes left, the 10th-ranked Hoyas pulled out a 78-76 victory at the Palestra on Scates' defense and -- surprise -- scoring, and clutch points at the end by guard John Duren.

Scates' heroics included a dramatic stuff shot with 1:16 left in the game, putting Georgetown ahead to stay as the Hoyas improved their record to 14-2.

There have been many outstanding games in this hallowed half of Eastern basketball. Today's surely ranks among the best, with two closely matched teams of similar unselfish styles seeking that winning extra.

Scates was that edge, playing a career-high 35 minutes, blocking a career-high nine shots and scoring 11 points (he had only 14 points in the past 14 games).

When the Quakers did get the ball inside, he made them adjust the trajectory of their shots. "He had as fine a defensive game as he ever had," Thompson said.

Scates' best previous game was in his sophomore year, when he scored 12 points (on six-of-six shooting), grabbed 11 rebounds and blocked five shots in a 66-64 loss to a fine Alabama team in the first round of the Carolina Classic.

Most of the time, Scates' main responsibility is as a sort of goaltender, hanging back to prevent easy baskets while his teammates apply their pressing defense. It's a role he fills without fanfare.

"He was much more dominant and played much longer than I expected," said Bob Weinhauer, the coach of 11-3 Penn, defending Ivy League champion.

"We rely a lot on our inside game," said Penn forward Tim Smith. "He took a lot of it away from us."

"You've got to think about him because he's swatting them away," added forward Tony Price, who was Penn's top scorer with 18 points, most of them from the perimeter. "He's not the most graceful player in the world, but he takes up a lot of space and you have to know where he is."

Georgetown surged to a nine-point lead, 53-44, before Shelton picked up two fouls in one possession and went to the bench. Shelton totaled 21 points. The score was even again in less than two minutes and neither team got more than three points ahead the rest of the game.

With the Hoyas trailing by 71-68, Eric Floyd tracked down a loose ball in the corner, sank a fallaway 20-footer and was fouled by reserve center Tom Liefsen, a freshman who had replaced starter Matt White (12 points, 14 rebounds) when he fouled out shortly before Shelton.

Floyd's free throw created a tie at 71 with five minutes to play. Two possessions later, Floyd missed a 20-foot baseline jumper that Thompson would have preferred the freshman not to take at that stage. Price scored a fastbreak layup and Penn led 73-71, with 4:06 left.

The Hoyas got the ball back when Leifsen made an errant pass from the side of the lane. Georgetown took a timeout with 2:50 left and came back playing tentatively, Duren and team captain Steve Martin both having to hustle to recover passes.

But Duren, who scored five of Georgetown's last seven points and assisted on the other basket, tied it at 73-all with a 20-foot jumper.

On the ensuing possession, on Smith's dribble, Scates held the Penn forward, who went to ths foul line for a one-and-one. He made the first and missed the second, but Leifsen got the rebound and put up a five-footer.

Scates got a couple of fingers on it, and when the Quakers finally recovered the ball, Leifsen was called for a three-second violation.

Again, Georgetown had trouble holding onto the ball. A Penn player deflected Duren's dribble at the foul line, and the Quakers swarmed around the Georgetown point guard.

Duren then released a perfect pass and Scates took it high above his head and dunked the ball two-handed. Georgetown led, 75-74, with 1:16 left.

At the other end Price dared to test Scates inside. Scates, however, was close enough to stretch, jump and deflect the ball slightly. Hoya freshman Jeff Bullis got the loose ball.

Penn wanted to give a foul, but the Quakers waited almost 40 seconds and fouled the wrong man, Duren, with 21 seconds to play. He made both for a 77-74 lead. Penn quickly came down court and Bobby Willis shot a twisting driving layup, but Leifsen touched the ball in the cylinder for an offensive goal-tending violation.

Penn called time with 14 seconds left. Price used his quickness to steal Martin's inbounds pass and fed Willis for a layup. With the score 77-76 and 10 seconds left, Penn took another timeout.

Following the Hoyas' inbound pass, Willis fouled Duren with two seconds left. Penn called time twice before Duren got a chance to take his two free throws for the intentional foul. He made the first and missed the second, half on purpose, he said.

In the second game of the doubleheader, Mickey Davila scored an eight-foot jump shot with two seconds left, his only field goal, to give Duquesne a 90-89 victory over La Salle.