They came here to prove their many doubters wrong. They came to prove to those who wondered what they were doing in the NCAA basketball tournament that they belonged.

Today, when the Navy band played the alma mater as the final buzzer sounded, 13,260 in the Dayton Arena stopped, stood and listened along with the basketball team that had just stunned them by blowing Southeastern Conference power Louisiana State right back to Baton Rouge.

The final score was 78-55 and an accurate indication of the stomping the Midshipmen administered in their first NCAA tournament game since 1960. It was their smarts, their savvy, their desire that brought the crowd to its feet. LSU, in the words of its coach, Dale Brown, "was completely embarrassed."

Having proven so emphatically that they belong, the Midshipmen (26-5) now get their first crack at Maryland in five seasons when they play the Terrapins Sunday in the second round of the Southeast Regional here.

"People who see this score will probably say that LSU stunk and Navy was lucky," Navy Coach Paul Evans said. "But it doesn't matter to us. We know what we've done."

LSU (19-10) did stink, but Navy was hardly lucky. It executed its game plan almost to perfection, packing its defense in to make the Tigers shoot jump shots, working the ball inside to Vernon Butler (20 points) and David Robinson (18 points, 18 rebounds) and getting a brilliant game from point guard Doug Wojcik. Wojcik had 18 points and eight assists and consistently beat LSU's second-half press.

"They were double-teaming me when I got the ball," Wojcik said. "Their point guard was quick but once I got by him, their two and three guys were, well, kind of slow to come over."

Everything LSU did today was at least a step slow. The day was perhaps best summed up for the Tigers early in the second half when Brown, who lost his 10th straight postseason game dating back to 1981, called substitute Oliver Robinson back for a final instruction.

"Oliver," Brown said, "you get Whitaker and tell John to get No. 5."

Kylor Whitaker is No. 5 for Navy. Guess what? Both LSU players went over to guard him.

"We heard that," Wojcik said. "He (Brown) was really lost."

Brown wasn't alone. Other than freshman John Williams (12 points on six-for-eight shooting), the Tigers were truly toothless. They shot 34 percent. Jerry Reynolds was one for eight, point guard Derrick Taylor was two for 13, wing Don Redden was one for five and Dennis Brown was four for 10.

"We just seemed burnt out," Dale Brown said. "I want to give Navy all the credit. They proved today that they are a good basketball team."

Navy believed it had proved long before today that it is a good team. But this was a chance to prove it to a few more people. Navy's coaches had seen on film that LSU did very little but shoot jump shots or force quick entry passes against a zone defense, so they packed in early from the start.

When Robinson began by hitting two short jump shots, that took away any chance that early jitters might get Navy in trouble. "We were a little worried that if we came out tentative, LSU might build a lead and then it might be a blowaway," Evans said. "They have the athletes to do that kind of thing."

Instead, despite shooting 38 percent the first half, Navy never trailed by more than 10-7 and led, 28-24, at intermission after Wojcik made a 10-footer against the press in the final minute.

"We thought we were in good shape at half," said Butler, who missed four of five shots in the first 20 minutes. "We knew we wouldn't shoot like that the whole game and still we were ahead."

At halftime, Evans spoke to Butler and Whitaker (one for three) and told them to relax, reminding them that defense would keep the team in the game. "I never bitch about shooting as long as the kids are taking good shots," Evans said. "I thought we were in a really good situation at the half. I told them, 'Take it easy and it will come.' "

It came, with remarkable ease. The second half began with Robinson's layup off Cliff Rees' steal, followed by Rees' two foul shots set up by Wojcik's steal. That made it 33-24. Reynolds tossed a brick and Wojcik hit from 17 feet. Rees got a layup off Wojcik's pretty pass and Butler got inside for two foul shots.

It was 39-24. Navy had scored 11 straight points, Brown already had used two timeouts and the game was over. The Tigers never got closer than 11. When they tried to press, Wojcik embarrassed them. From 63-46, he scored eight straight points.

Whitaker had 13 points, making nine of 10 foul shots down the stretch as the Midshipmen made 34 of 43 for the game and shot 62 percent from the field in the second half. By the finish, Evans had cleared his bench to keep the score from getting worse. "Did I think we could blow them out like that?" Evans said. "I didn't think we could blow anybody out like that."

LSU, to a man, was stunned. "We overlooked them," John Williams said. "We just didn't think anything like this could happen to us."

Brown, who had said Thursday that he liked his team's "relaxed intensity," had no excuses for the horrendous showing. "It's like being the father of a teen-ager with a drug problem," he said. "You have to take the responsibility."

"When I saw the draw, I thought they were seeded too high (fourth in the region) and we were seeded too low (13th)," Evans said. "I guess, as it turned out, I was probably right."

Brown, whose players admitted this week they knew almost nothing about Navy, said before the game that "everyone expects us to be going to Birmingham (for the regional) next week. But if we're not ready to play, we'll be at McDonald's in Baton Rouge before sundown Friday."

As Brown was consuming his Big Mac tonight, Evans and the Midshipmen still were here, dining on anything they chose. They more than earned a special meal today.