If the University of Wisconsin women’s hockey team is going to successfully defend its national championship, it may have to do so with a gaping hole in its lineup.

Wisconsin coach Mark Johnson said Tuesday that junior defenseman Stefanie McKeough is day-to-day with an apparent concussion, making her questionable for an NCAA Frozen Four semifinal matchup Friday with Boston College at Amsoil Arena in Duluth, Minn.

McKeough is the newly-crowned Defensive Player of the Year in the Western Collegiate Hockey Association who routinely plays 25 to 27 minutes a game, runs the power play, and provides a cool, steady hand when it comes to transitioning the Badgers from defense to offense.

Johnson used some high-profile references to underscore McKeough’s importance to his operation.

“You take an NHL lineup and (Chris) Pronger’s not playing for Philadelphia, or (first-team All-American) Justin Schultz isn’t playing (for the UW men’s team) and they’re going to look a little different,” he said of the teams.

“But that’s part of our world. You just don’t know what’s going to happen on a daily basis, and that’s why coaches stress out a lot, especially this time of year.”

McKeough, from Carlsbad Springs, Ont., is the top-scoring defenseman for Wisconsin with four goals, 18 assists and 22 points. She sat atop a stationary bike and watched practice Tuesday, one day before the club was scheduled to bus to Duluth in pursuit of its fifth NCAA title.

The Badgers have a good deal of experience on defense — senior Brittany Haverstock and juniors Alev Kelter and Saige Pacholok are all dependable Frozen Four veterans — but Johnson said McKeough “has that competitive level that’s tough (for opponents) to match.”

McKeough, who is plus-24 this season and plus-83 in 99 career games, was injured March 2 during a 3-1 loss to Minnesota-Duluth in the WCHA playoff semifinal game. Her absence was felt on a multitude of fronts, but particularly on the power play, which went 1-for-9.

The unit, which ranks fourth in the nation with a conversion rate of 23.3, subsequently went 0-for-3 without McKeough during a 3-1 victory over Mercyhurst in an NCAA quarterfinal last Saturday.

“But as I told the group, championship teams don’t make excuses,” Johnson said. “You move on and see what we can put on the ice.”

The top-ranked Badgers (32-4-2 overall) have some formidable characters to lean on when they face BC — junior center and Patty Kazmaier Award finalist Brianna Decker, senior center and two-time All-American Hilary Knight, senior winger and 30-goal scorer Brooke Ammerman, senior winger and 50-point producer Carolyne Prévost, and sophomore goaltending savant Alex Rigsby — but having McKeough would ease their burdens considerably.

Should Wisconsin get past the Eagles, it would face either Cornell or WCHA rival Minnesota for the national title Sunday.

“Sometimes you have to win ugly, but that’s OK this time of year,” Johnson said. “You’re trying to figure out how to beat the other team by a goal. It doesn’t have to be pretty, just effective.

“This time of year, you’ll bend at times. You just can’t break.”