Rosemount defeated Roseville 35-28 in a thrilling state Class 6A semifinal in the Metrodome in November 2013. Now, the quarterbacks in that shootout will meet again as college rivals when St. John’s and St. Thomas play at 1:10 p.m. Saturday at Target Field. First, Patrick Reusse takes a look at St. John’s quarterback and former Rosemount star Jackson Erdmann of St. John’s. On Saturday, Reusse will write about Jacques Perra, the St. Thomas quarterback and former Roseville standout.

Jackson Erdmann knew it was a long shot in 2014 when he sent an e-mail to Ricky Rahne, the quarterbacks coach at Penn State. He gave his résumé and offered scouting video on the outside chance the Nittany Lions might be interested in a quarterback from Rosemount High School in Minnesota.

Erdmann had considerable success with the Irish, playing for his father, Jeff. Rosemount reached the Class 6A state final vs. Eden Prairie in 2013. He was the Star Tribune’s All-Metro quarterback as a senior in 2014, passing for 2,044 yards and 24 touchdowns.

He finished his high school career with a 25-5 record as a starter. He also finished with a broken fibula suffered in an opening playoff loss to Lakeville North.

Erdmann limped through that game before the injury was diagnosed. Earlier in the year, he had recovered from mononucleosis, and then dealt with a recurrence of a malady called acute cerebellar ataxia.

Considering all of that, it had to be a really persuasive e-mail that Erdmann sent to get Penn State to get a look as a walk-on. He was invited for a visit in February 2015, was offered one of the Nittany Lions’ preferred walk-on spots, and seized the opportunity.

What did Jackson’s father and coach think of this?

“Shoot for the stars,’’ Jeff Erdmann said. “Don’t be satisfied to just exist. Go for it.’’

Jeff Erdmann obviously is taking that advice for himself, since he’s now campaigning for the DFL nomination for Congress in District 2, while also coaching and teaching at Rosemount.

Gotta be there: 34,000 tickets sold for Johnnies-Tommies at Target Field

Jeff says that his son had a wonderful experience at Penn State, even though it was a chaotic year in State College. Penn State went 7-6 with no important wins, and coach James Franklin was facing high heat.

Christian Hackenberg had a mediocre junior season as Penn State’s pocket-passing quarterback. Franklin fired offensive coordinator John Donovan and brought in Joe Moorhead, Fordham’s head coach, to install a run-pass option offense.

That sent Hackenberg to the NFL draft. And it sent Erdmann back to Minnesota, since the odds of seeing the field for Penn State went from long to non-existent with the change in offense.

“I’m not a runner,’’ he said this week. “I will run, but I’m not going to run away from anybody in a foot race.’’

Erdmann almost wound up at St. John’s out of high school. He called Johnnies coach Gary Fasching in December 2015 to find out if the opportunity still existed. The answer was yes. He enrolled in Collegeville and participated in 2016 spring practice.

Edrmann gained the starting job and threw 11 touchdown passes in three victories to open the 2016 season. That brought St. Thomas to Collegeville. Erdmann threw a 68-yard touchdown to Evan Clark early to tie the score 7-7. After that, he was under siege, and the Tommies defeated the Johnnies 33-21.

Erdmann took a hard blow in the first half. He didn’t think that much of it and was cleared to keep playing.

Later, it was diagnosed as a concussion, and it triggered another episode of the childhood version of ataxia that he has dealt with.

Acute cerebellar ataxia doesn’t sound like a day at the beach for a football player. More than anything, it causes a loss of equilibrium. The treatment apparently is to let this ataxia run its course.

Erdmann missed a month last fall, as Ben Alvord took over as the quarterback. Erdmann was full go for the playoffs — a victory over Wisconsin-Platteville, then a loss to UW-Oshkosh.

Erdmann and Alvord both have sat for stretches as the Johnnies have won three blowouts, including the 98-0 embarrassment vs. St. Scholastica to start the season.

Now, things get serious: The Tommies, with their quarterback, Jacques Perra, in his second year at St. Thomas and first as a starter after transferring from Minnesota.

“I only know Jacques from playing against him in high school in 2013,’’ Erdmann said. “I did send him a message late in 2015, when I heard he might be transferring to an MIAC school.’’

Checking to make sure you weren’t going to wind up at the same school? “Something like that,’’ Erdmann said.

They weren’t. Erdmann became a Johnnie, and Perra became a Tommie, and part of a Division III rivalry more intriguing than ever, as 30,000-plus fans will prove on Saturday.