Mathis played forward Jalen Smith and guard Darryl Morsell in high school.
Maryland is looking to bounce back from its first home loss of the season.
The junior guard is having the best season of his career for the Terps.
The Terps control their own destiny en route to a Big Ten regular-season title.
The Spartans prevented the Terps from clinching at least a share of the Big Ten regular-season title.
The Terps and Spartans will square off Saturday in primetime.
“When he gets going, he makes the entire team better."
“It was a huge shot,” Jalen Smith said. “Probably one of the biggest shots he’s hit in his life.”
Morsell had shot just 3-of-11 from the field before his game-winner.
Maryland and Minnesota meet Wednesday night for the only time this season.