Before Friday, St. Thomas Academy and South St. Paul hadn’t shared a football field since 2016.

Coach Dan O’Brien hadn’t come to the Cadets program. Manuel Spreigl was still a South St. Paul assistant, living out what O’Brien later learned about the rivalry these programs share.

Fitting then, that the key player in St. Thomas Academy’s 18-6 victory was sophomore running back Savion Lopez. He attended school in South St. Paul as an eighth-grader. On Friday, he posted more than 100 yards in the second half alone, running past or over Packers players he once called youth football teammates.

“We knew it was going to be a big game, a fight to the end,” Lopez said. “We didn’t give up hope. We knew we could pick it up because that’s the team we are. We put in more work than anybody in this conference, on and off the field.”

In the first half, blunders by South St. Paul’s punt kick and punt return units gave the Cadets great starting field position. But the Packers defense stiffened as St. Thomas Academy twice marched inside the 10-yard line. All the Cadets managed were two field goal attempts, one good and one wide.

The Cadets held a tenuous 3-0 halftime lead.

“I’m very frustrated with not getting the points,” O’Brien said. “Once we got back to doing what St. Thomas Academy does, then I think we were OK.”

That meant increasing Lopez’s workload. His 9-yard rushing touchdown late in the third quarter gave the Cadets a 10-0 lead. He added a 21-yard scoring run in the fourth quarter.

South St. Paul’s Alonzo Dodd returned the ensuing kickoff for a score to avoid the shutout.

“Our defense was amazing,” Lopez said. “They gave us time to come back and rethink things, to do our thing in the second half.”

South St. Paul’s triple-option offense couldn’t do its thing with waves of Cadets defenders crashing down.

“They were so fast with their penetration that we couldn’t get to where we needed to go,” Spreigl said.

Spreigl is in his first season as Chad Sexauer’s successor. A 1998 South St. Paul graduate, Spreigl aims to build on the foundation Sexauer built the past 17 seasons. The Packers made seven state tournament appearances and were runners-up at the 2015 Class 4A Prep Bowl.

Those Packers teams played big-boy football, something St. Thomas Academy brought Friday.

“We matched their physicality,” O’Brien said. “And when your defense doesn’t give up points, that usually means it’s going to be a good night.”