Maryland, its high-powered offense bogged down by penalties, stayed in the game with excellent man-down defense and then scored five straight goals late in the fourth quarter and defeated Navy, 16-13, in a battle of unbeaten lacrosse powers yesterday before 15,103 at Byrd Stadium.

The outcome left Navy Coach Richard Szlasa second-guessing his strategy after the Mids took a 13-11 lead with nine minutes to play.

"The game wasn't lost by the players," Szlasa said. "It was lost on a couple of mistakes by me. We could have sat on it (the two-goal lead). It was a mistake in judgement on my part."

Maryland committed 17 penalities totaling 15 minutes - one-fourth of the game. When the Terps were at full strength, they played like the nation's No. 2-ranked team that averages almost 20 goals per game.

They made up the two-goal deficit in six seconds, on goals by Pete Worstell and John Lamon. The latter came on an assist from Worstell, who scored five goals, three in the final period.

Less than two minutes later, Worstell scored the go-ahead goal. As a teammate ran off the field, followed by his Navy defender, Worstell ran on the field from the other end of the penalty box from which all substitutes enter play.

A defenseman threw a 50-yard pass to Worstell on the run and he beat Navy goalie Jeff Johnson for the unassisted goal at 10:27. Another unassitstd Worstell goal clinched the win at 14:15.

Attackmen Brendan Schneck and Mike Buzzell led the Mids, who took a 7-0 record and No. 4 ranking into the game. they combined for eight goals and seven assists.

In the roughhouse first quarter, Navy controlled the ball and took a 5-2 lead on three extra-man goals by Schneck, all assisted by Buzzell. But Maryland made some adjustments in its man-down defense, and the Mids failed to score another extra-man goal.

Maryland Coach Buddy Beardmore praised the goaltending of Sandy Kapatos and Bryant Waters, who shuttled in and out of the game, depending on the defensive situation, and of his entire man-down defense.

"You have to give credit to the defense," he said. The team defense was the name of the game in the third period. It was one of my sweetest victories - to be down like that and come back and then come back again."

Neither Beardmore nor his players wanted to give away secrets because the same teams may face each other again in next month's NCAA tournment. But attackman Bob Boniello did say:

"We worked on it in practice all week. It was a whole completely different defense than we normally use. We try to cut off Schneck and Buzzell. We knew if we cut them off, the Navy offense couldn't work."

But neither could Maryland's for much of the afternoon. At one stage, the Terps went scoreless for 19 1/2 minutes.

"That's what wooried me," said Bomiello, the Terps top scorer. "We usually don't go that long withou scoring."

He said the large number of penalities was not because the aggressive Terps were trying to intimidate the young Mids.

"We just came out overpsyched," Boniello said. "We came out running around like chickens with their heads cut off."