TOWSON, Md. - It took nearly the entire six minutes of two overtimes for Rachel Manson to emerge as the hero for Penn tonight. But she did, and the Quakers are going to the NCAA Division I women's lacrosse championship game at 7 p.m. Sunday.

Manson, a senior attacker, scored her second goal of the night with 42 seconds remaining in the second three-minute overtime at Towson University's Johnny Unitas Stadium to push Penn past stubborn Duke, 9-8, in a dramatic semifinal game.

The victory sent the second-seeded Quakers (17-1) into the title game against top-seeded Northwestern, a 16-8 winner over Syracuse in the night's first semifinal. The Quakers defeated Northwestern (20-1), the three-time defending champions, 11-7, on April 27.

The winning goal came when Giulia Giordano, a freshman from Moorestown High, had a free position and passed to Manson, who whipped a shot past Duke goalie Kim Imbesi.

"It was pretty sweet," Manson said. "But I think I blacked out on that goal. I can't tell you how it happened. I was just glad for the team."

Imbesi knew how it happened.

"With a shot like that, it was a guessing game," she said. "I guessed low and wide, and she shot above me."

Things looked good for Penn with less than six minutes left in regulation when Melissa Lehman scored a go-ahead goal, her second of the game, to give Penn an 8-7 lead. But Duke's Lindsay Gilbride matched Lehman's score with only 60 seconds to play in regulation.

That goal dismayed Penn goalie Sarah Waxman.

"I really wanted to win it in regulation," she said.

So the game boiled over into overtime, and Manson capped a come-from-behind victory - Penn trailed, 7-4, midway in the second half - with her clutch goal.

"It was a little stressful at 7-4," Penn coach Karin Brower said. "But our offense is disciplined and we chipped back into the game."

Duke's Carolyn Davis scored twice, at 25 minutes, 9 seconds and 22:34 of the second half, and Duke led by three, 7-4. But goals from Kaitlyn Lombardo, Lehman and Ali DeLuca knotted the score with 11:38 remaining in regulation.

Penn, which has claimed five national titles - women's squash (2000), women's fencing (1986) and men's fencing (1953, 1969, 1981) - has never taken the crown in women's lacrosse.

This year, Penn registered a school-record 15 straight victories, including tonight's, to better the 13-game winning streak the Quakers enjoyed last season on their way to the final four. The Quakers, who hosted the event last year, went down to Northwestern in those semifinals by 12-2.

Unlike last season, when Penn failed to score in the first half against the eventual champions, the Quakers wasted no time tonight getting on the scoreboard. One minute into the game, Manson took a pass from Allison Ambrozy and scored to give her team the first goal of the game.

Giordano accounted for the first goal of the second half when she went flying toward the goal and caught a pass from Chelsea Kocis, who was coming around from behind the net.

In the first game, Syracuse (18-3) received three goals from Megan Mosenson, a graduate of Great Valley High.

Contact staff writer Kevin Tatum at 215-854-2583 or ktatum@phillynews.com.