Larissa Johnson had plenty of reasons to celebrate Friday night. First, the Northern High School senior turned 18 that day, and to mark the occasion she had invited her girls basketball teammates to her house for a party that night.

But before Johnson and the Patriots headed to her house to nosh on pizza and chicken, they defeated visiting McDonough, 39-24, giving them an important Southern Maryland Athletic Conference win and another reason to be festive.

"Everyone at school kind of knew it was my birthday, but I didn't really do anything during the day [to celebrate]," said Johnson, who scored 14 points and added four steals, three assists and two rebounds in the win. "I just wanted to concentrate on the game, because it was a big game for us."

The victory allowed Northern (8-2, 5-0 SMAC) to stay tied atop the conference standings with Thomas Stone (11-0, 5-0), which defeated La Plata, 61-49, on Friday. Northern hasn't lost a conference game in the past three seasons, but with three starters gone from last season's 24-3 team, and McDonough and Thomas Stone off to good starts, the Patriots could feel some pressure. The Patriots play the Cougars on Wednesday night.

McDonough (5-6, 3-2) had won five of its last six games before Wednesday's surprising loss to Calvert (4-7, 3-2). And the Rams gave the Patriots a test Friday night, tying the game midway through the third quarter.

But Northern, led by Johnson, was able to reignite its offense late in the third quarter and ran away with the game in the fourth. Johnson scored 12 of her points in the second half, including seven in the fourth quarter.

"I think Larissa made the difference," Northern Coach Rod Stewart said. "She stopped being timid. She stopped passing off to other people. She could really take the ball and beat people in the press. She was aggressive."

Northern had led 14-8 at halftime after both teams got off to a sloppy start. McDonough began the second half with a 6-0 run, forcing Stewart to call timeout with 4 minutes 55 seconds remaining in the third quarter.

Two minutes later, Donna Lyles (10 points) hit a short baseline jumper to give Northern the lead, sparking a 9-2 Northern run to end the quarter. The Patriots then iced the game with an 11-2 run during the fourth quarter.

Northern's primary focus on defense was McDonough forward Lori Ashton, Stewart said, and the Patriots held her to 10 points and eight rebounds. No other Ram had more than five points.

After the game, Stewart rewarded his team's defensive effort by canceling the practice scheduled for yesterday. Johnson said she would take advantage of th at--she and her teammates planned to party until 1 a.m. at her house.

"I'm 18 now, I can do that," she said with a smile.

McDonough (5-6, 3-2)--Lufriu 1 1-2 3, Karimi 1 0-0 2, Briscoe 2 1-2 5, Blake 0 2-2 2, Ashton 4 2-2 10, Savoy 0 1-2 1, Thomas 0 1-2 1. Totals 8 8-12 24.

Northern (8-2, 5-0)--S. Smith 1 0-0 2, Johnson 6 2-3 14, Lyles 5 0-0 10, T. Smith 1 0-0 2, Simpkin 1 2-2 4, Gray 2 3-6 7. Totals 16 7-11 39.

Halftime: Northern, 14-8.