Duke too often showed its youth and Georgetown mostly didn't, and the Hoyas' all-American played like one while the Blue Devils' centerpiece player usually didn't.

When Georgetown finally was done recapturing the kind of frenzied, glorious evening that its band of freshmen wasn't supposed to be able to help the veterans produce, the sixth-ranked Hoyas had emerged with a gritty 79-74 ACC-Big East Challenge victory over No. 5 Duke before 19,035 at sold-out Capital Centre.

In the first game of the night, St. John's defeated Georgia Tech in overtime, 73-72 (Story, Page E4). With two games to go in the series, the Big East leads, 5-1.

Georgetown (4-0) led virtually throughout, but the Hoyas were pressed late as a onetime 16-point second-half lead became a one-point edge in the final minute. The Blue Devils (5-2), however, couldn't get over the final hump, and Alonzo Mourning's brilliant 22-point, 10-rebound night was not wasted.

Christian Laettner had a sporadic, 14-point performance -- on five-of-22 field goal shooting -- for Duke, which was led by guard Billy McCaffrey's 20 points and reserve forward Brian Davis's 18.

The Blue Devils, who were harassed into 33 percent shooting but forced 25 turnovers, pulled to 75-74 with 29.4 seconds to play, but Mourning blocked Davis's driving attempt with 12 seconds left.

"When two teams play defense like we do, it's not going to be very pretty but it will be very intense," Blue Devils Coach Mike Krzyzewski said. "This was unusually intense. . . . For about 11 minutes in the first half, we were just disjointed. We took jump shots and they took us off our game."

Mourning was the primary disrupter. He had special incentive, for the previous time these teams met -- in the East regional final of the 1989 NCAA tournament -- Laettner upstaged him in their freshman duel. The lingering image of that contest was Phil Henderson's dunk over Mourning's outstretched hand, and Mourning said he "learned a lot from that game."

"I took it in stride," said Mourning, who made eight of 12 field goal attempts last night and paved the way early on with a 17-point, seven-rebound first half. "Now I'm more mature. . . . It was a great game, but I'm not going to say it was my most satisfying game because we didn't win a championship or anything."

Said Laettner, a teammate of Mourning on last summer's U.S. National Team coached by Krzyzewski: "That was vintage Alonzo. He dominated, and he and {Dikembe} Mutumbo took us out of our offense."

All that Duke feared might go wrong did go wrong during the early going as the Hoyas frantically raced to a 12-point cushion. The Blue Devils turned over the ball against pressure defenses and failed to keep the Hoyas from gathering offensive rebounds.

But mostly, Duke's players just watched as Mourning did everything. The junior forward dunked and nailed jump shots on one end of the floor and swatted away passes and field goal attempts alike at the other.

Laettner seemed overwhelmed inside at times, Blue Devils point guard Bobby Hurley was wilting beneath Georgetown's defensive assaults. "We had them on the ropes all game," Mourning said. "We just never finished them off."

Mourning ignited Georgetown with a pair of followup dunks, and Duke went 10 sloppy possessions as a Hoyas' surge turned a 10-10 game into a 22-10 advantage. The Blue Devils -- committed to man-to-man defense -- rotated defenders but couldn't find an answer.

Still, Duke regrouped. Goaltending calls against Mourning and 7-foot-2 Dikembe Mutombo(14 points, 13 rebounds) drew the Blue Devils to 22-14 before Mourning posted up 6-6 Davis for a three-point play. An 8-1 surge sparked by Davis brought the Blue Devils closer. It was 36-30 at the break.

McCaffrey, a slight sophomore guard given greater leeway this year by Krzyzewski to launch jumpers, heated up in the early second half. McCaffrey had 10 of Duke's first 13 points then, narrowing the deficit to 47-43.

But again, Georgetown replied. This time it was Mutombo to the fore, providing eight quick points, and the Hoyas forged another run.

This burst, fueled by freshmen Charles Harrison and Robert Churchwell (11 points), was a 15-4 undoing of the Blue Devils capped by Mourning's hook in the lane for his first points of the second half, and it left Georgetown ahead by 62-46.

Davis and Hoya Brian Kelly squared off in a flareup that prefaced a technical on the Duke bench, and the Hoyas seemed to have a firm grip. But Mutombo left the floor with leg cramps and Hoyas freshman point guard Joey Brown fouled out with 5:18 to go and Duke mounted a final scare.

Hurley's three-point jumper with :57 left got it to 75-72. Davis's foul shots at :29.4 got Duke within one. Harrison then made two free throws, and Mourning blocked Davis.