Coach Joe Spallina promised Stony Brook would become an elite women's lacrosse team when he arrived four years ago from Adelphi. That moment arrived Sunday when the host Seawolves upset No. 5 Northwestern, 11-9.

"Landmark win, it's monumental," Spallina said. "For us to beat Northwestern, a team that won [seven] national championships [including one at LaValle Stadium in 2012], every one of our girls grew up watching them win national championships. We're playing the brand, too."

The victory for No. 9 Stony Brook could mean a home game in the NCAA Tournament next month if the favored Seawolves win the America East Conference title.

Stony Brook (13-1) had a 5-0 lead by 17:44 of the first half. Courtney Murphy and Dorrien Van Dyke combined to score four of the goals.

"I think when we came out 5-0 and punched them in the mouth, they were a little stunned," Van Dyke said.

The Seawolves led 5-3 at halftime and kept their composure when Northwestern mounted a comeback with just under six minutes left. Trailing 10-5, Northwestern (9-4) scored three straight goals to close within 10-8 with 5:29 left, but Kristin Yevoli scored for Stony Brook with 3:10 left. Kara Mupo, who was coached by Spallina in the past, scored the final goal for Northwestern at 1:35.

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"They went on a little run, but we faced adversity really well," said Murphy, who had three goals and an assist. "We didn't get down, we knew we had control of the game since the start. We just believed in ourselves. We got the ball back and took care of it. Even when they came back and scored, we always answered with a goal of our own."

Freshman Kylie Ohlmiller led Stony Brook with four goals and two assists. A year ago, she was playing at Islip High School. If she was nervous, it didn't show.

"There's no time for it when you play these big games, big teams," she said. "It is a big transition, but I have all these girls who have experience with the big games around me."