They stretch their limbs, they dive, they do whatever it takes to put their bodies between the puck and the net, as defensemen are expected to do. Then the Gophers defense does the unexpected.

The unit's unmatched skating ability and discipline are the foundation on which the Gophers built a run into Thursday's Frozen Four semifinal against North Dakota in Philadelphia.

The Gophers defense has given up only 78 goals in 39 games, limiting scoring chances for a stellar goaltender and providing a reliable complement to a speedy offense.

"Team defense is probably more of our foundation than an offensive team this year," Gophers coach Don Lucia said. "I think the strength of the back end for us is the skating ability, their reach of the stick … and being able to get the puck out of our zone in a hurry.

"It has been a group of five. … I think the guys understand and are willing to block some shots when we need to do that. We don't take a lot of penalties, so we don't put ourselves in a bad situation as far as discipline on the ice."

The Gophers are No. 2 in the nation in team defense, giving up an average of two goals per game. Among the other Frozen Four teams, Union is No. 4 (2.05 goals-against average), Boston College No. 8 (2.28) and North Dakota No. 16 (2.44).

The Gophers are near the lowest in the nation in penalties minutes per game at No. 55 (8.8). North Dakota has the most penalties of the teams in Frozen Four field. It is No. 18 in the country (12.8).

Lucia alluded regularly to his dependable defense throughout the season. Three goals will translate to a win most nights, he reminded the skaters.

With this in mind, Lucia sought out to strengthen team defense even more and drew inspiration from the Winter Olympics. He pointed out the countless blocked shots Team USA's defensemen and forwards were willing to endure in their win over Russia. Lucia challenged his players to lay everything on the line the same way.

Since that call to action the Gophers have allowed more than two goals in a game just three times. They gave up three or more goals seven times in the first four months of the season.

"I think we have a great emphasis on defense first," senior defenseman Justin Holl said. "I also think as a defensive core we pride ourselves on being able to chip in offensively, but those offensive chances are created in the D-zone by shutting it down quickly and transitioning the puck."

Without size and overt physicality, the Gophers defensemen rely on their ability to skate, move the puck and avoid forechecks. Sophomore defenseman Brady Skjei said most of the blue-liners can fly, and senior defenseman Jake Parenteau said this creates a trust among the group.

Seniors Parenteau and Holl have taken on a role of support for their defensive partners and standout sophomores Mike Reilly and Skjei. Junior defenseman Ben Marshall has stepped into a role of playing right and left defense with the Gophers freshmen defensemen, Michael Brodzinski and Jake Bischoff.

The unselfish group effort allows each of the seven defensemen to excel at what he does best, associate head coach Mike Guentzel said.

The most obvious success has come from the expedited development of Reilly and Skjei. Reilly has become one of the Gophers' top scorers from the blue line with 32 points (nine goals, 23 assists). Skjei's big frame and quality skating limits the impact of bigger opponents.

"I think we want to be a great puck possession team, but we've got to be able to defend," Reilly said. "We can trust [goaltender Adam Wilcox] to make a big save, but we've got to limit those quality chances and if we do that we're going to be letting in one or two a night, and that's our goal and that's what Wilcox wants as well."

It's easy to figure out where the drive for better defense begins. Each defensemen and even the forwards find ways to mention defensive coach Guentzel when the subject is their success. Guentzel is in his third season back with the Gophers and already has two Frozen Four appearances and three conference championships to add to his résumé.

The former Gophers defenseman helped re-prioritize the importance of defense in the program through a hard-nosed approach. He expects the best out of his players, and if they won't give it, he'll find a way to pull it out.

The players like it that way, especially after three years of results.

"We put an emphasis and premium on having skating defensemen that can defend and that can get the puck out of our end. … This year's group fits well together," Guentzel said. "I have a belief in the way we should play, and they understand my expectations and get after it. I'm critical, I'm analytical, I'm a lot of different things to these kids, but they understand my expectation level and I hold them accountable and they hold me accountable."