The Maryland women’s lacrosse team entered the NCAA lacrosse tournament with the fifth-best offense in the nation, averaging close to 15 goals per game. But through 21 minutes Saturday against Princeton, the top-ranked Terrapins had scored just once and had seen their attack stymied by a combination of nerves and sloppy passing.

More important, Maryland faced a two-goal deficit against the underdog Tigers, a notion that is distinctly foreign to the defending national champions.

But as has been the case all season, the Terrapins’ balanced attack wouldn’t be held down for long. Maryland closed the first half with a seven-goal barrage that took less than six minutes and cruised to a 15-6 win over Princeton in an NCAA quarterfinal at the Field Hockey and Lacrosse Complex in College Park.

The victory catapults the Terrapins to the national semifinals for the third consecutive season and the 18th time in program history. They will face Duke, a 13-9 winner over Florida, in Stony Brook, N.Y., on Friday.

Sophomore Katie Schwarzmann led the charge for Maryland with four goals and two assists. Senior Sarah Mollison also chipped in four goals, while junior Kristy Black and Laura Merrifield had hat tricks.

“It was an energy thing for us. Everyone looked like they were afraid to have the ball for part of the first half,” said Coach Cathy Reese. “I just felt like we needed to calm down a little bit, have confidence and believe in ourselves and what we’re capable of doing.”

Maryland has lost just three games over the past three seasons, and the Terrapins enter the national semifinals with 30 wins in their past 31 games. That includes last year’s national championship victory when the Terrapins defeated Northwestern and ended the Wildcats’ five-year run as champion.

This year, though, a familiar type of pressure has returned to a program that already has an NCAA record 10 national championships. Maryland (20-1) has been atop the women’s lacrosse polls from the moment this season began, and Mollison admitted “it’s a bit of a relief now” that the Terrapins are back in the Final Four.

Those emotions were evident during the opening moments Saturday as Maryland struggled to control draws and suffered through an uncharacteristic number of turnovers. Then, 15 minutes into the first half, Princeton’s Cassie Pyle (St. Stephen’s/St. Agnes) scored her second goal of the game to give the Tigers a 3-1 lead.

From there, though, Maryland goalie Brittany Dipper quashed any hope for an upset by the Tigers (12-7). She finished with a career-high 15 saves, and her performance allowed the Terrapins to score 13 of the game’s next 14 goals.

“Dipper just had our number,” said Princeton Coach Chris Sailor, whose team lost to Maryland, 17-10, last month.

It was Mollison, the ACC’s player of the year, who gave the Terrapins the lead for good with just less than eight minutes left before halftime. She then scored three straight goals in a span of 30 seconds, capping the sequence with a fast-break tally that put Maryland ahead, 8-3, late in the first half.

The surge moved Mollison into fifth place on the school’s all-time career points list.

“It doesn’t matter. I don’t care,” said Mollison, when told of her accomplishment. “We’re going to the final four. That’s all that matters.”