The only defensive strategy that seemed to work against the Gophers women's hockey team on Saturday was an unorthodox one, to say the least: the empty net.

The Gophers hope to get another chance to work on it at the Frozen Four.

Second-ranked Minnesota scored five goals against a slow-to-gel defense and a pair of beleaguered North Dakota goaltenders, and easily advanced to their third NCAA Frozen Four in four years with a 5-1 quarterfinal victory over sixth-ranked UND at Ridder Arena.

The Gophers will face third-ranked Cornell -- which survived a three-overtime quarterfinal, 8-7, against Boston University on Saturday -- in the national semifinals next Friday in Duluth. Boston College, which eliminated St. Lawrence 6-3, will face top-ranked defending-champion Wisconsin, which ousted Mercyhurst 3-1, in the other semifinal.

Five different Gophers scored against North Dakota, including a bizarre behind-the-defense's-back goal by Emily West that gave Minnesota an early lead, and a short-handed breakaway by Amanda Kessel made sweeter by some ex-teammate rivalry. But when North Dakota, trailing by five goals midway through the third period, left its net untended for a whopping 7:37, the Gophers suddenly were unable to connect.

"Obviously we need some more work on our empty-net shooting," Gophers coach Brad Frost joked afterward of his team's rash of misfires at the open goal. An empty net "might be a strategy Cornell looks at."

The Gophers' strategy of taking an early lead and then relying on goalie Noora Raty is an effective one, too. Raty allowed a point-blank goal with 6:07 to play, ending a span of 246 minutes and 53 seconds without letting the puck get past her, more than four games worth of shutout.

"She's just awesome out there," Kessel said of Raty. "She's the best goalie around in college hockey."

And Kessel's one of the best scorers. The junior forward made an athletic play midway through the second period that seemed to break North Dakota's spirit. As sisters Joce- lyne Lamoureux and Monique Lamoureux-Kolls -- Kessel's former teammates at Shattuck- St. Mary's in Faribault, Minn., and ex-Gophers, too -- tried to set up a power play, Kessel pounced on a sloppy pass and streaked the other way. She shot the puck into the upper left corner of the net for a short-handed goal as Jocelyne Lamoureux tried to pull her down from behind.

"I saw an opening, and I just found a spot," Kessel said. "I even heard them yelling at each other on the play, [and it] kind of drove me to want to score more. Being their top two players that gave over the puck there, and one chasing me, that just gave me more momentum to try to bury it. I can't repeat the words that they said, but they were pretty angry with each other on that play."

Not as angry as UND was with each other after allowing a fluky soft goal only 88 seconds into the game, a slow 70-footer by West that bounded past defenders who had their backs turned, and through Stephanie Ney, North Dakota's stunned goalie. Ney was quickly replaced by Jorid Dagfinrud, but the Gophers took advantage of one mistake after another to build their lead. Sarah Erickson had a goal and two assists to lead the Gophers (32-5-2) into the Frozen Four once more.