A Frozen Four team last year, Notre Dame entered the 2017-18 season with a big question: Who would replace Cal Petersen in goal?

Petersen turned pro after leading the Fighting Irish to the national semifinals, posting a 23-12-5 record, a 2.22 goals-against average and a .926 save percentage along the way. He started all 40 games, so Notre Dame had a big spot to fill.

Enter Cale Morris, a sophomore who is one-upping Petersen.

Morris, who played in only one game last season, backstopped the Fighting Irish to a 4-3 overtime victory over Michigan in the second Frozen Four semifinal on Thursday night at Xcel Energy Center. In improving to 27-7-1, he made 25 saves and was key to killing four consecutive penalties against Notre Dame in the second and third periods. Entering the game, his .945 save percentage led the nation, and his 1.91 GAA was sixth.

Morris is a big reason why Notre Dame won the Big Ten title in its first year in the conference, and now he has the Fighting Irish one win from their first national championship. They play Minnesota Duluth on Saturday night.

“He’s been a rock all year,’’ Notre Dame senior captain Jake Evans said. “Even when he lets in one goal, we just build our confidence because we know he’s not going to let anymore in right away. … He’s definitely been a key to our success.’’

Notre Dame coach Jeff Jackson, who recruited Morris to be Petersen’s heir apparent, credits his goalie for having an even demeanor.

“The best attribute about Cale is he’s in control. He’s emotionally, mentally and physically in control,’’ Jackson said. “He reminds me a lot of the kid we had last year [Petersen]. He doesn’t get rattled. It’s all about his poise.’’

Morris credits Petersen for being his mentor. “I knew it was going to be a great opportunity for me to soak in as much knowledge about the game on and off the ice,’’ he said Wednesday. “… He definitely took me under his wing.’’

Winning rubs off

Michigan, which used a strong second half of the season to finish third in the Big Ten and earn an NCAA at-large berth, drew motivation from the school’s men’s basketball team, the NCAA tournament runner-up to Villanova.

“Seeing the stuff that they did, being unranked in January and then kind of working their way up, very similar to us,’’ goalie Hayden Lavigne said. “Watching [other Michigan] teams shows us we can do the same thing.’’

Wolverines coach Mel Pearson embraces the success of other on-campus teams: “As far as football and basketball [success], it only adds to our recruiting.’’