St. John Bosco (Bellflower, Calif.), the nation's No. 4 team, made a stirring comeback to beat Chandler (Ariz.) 52-31, but the victory may have come at quite a price.

Bosco's highly touted junior quarterback Josh Rosen hurt his right shoulder in the second quarter, but Andrew Katnik came to the rescue to lift the team to the wild victory in a game that featured almost 1,000 yards.

According to the Los Angeles Times, Katnik completed 10 of 11 passes for 121 yards and two touchdowns while Rosen sat on the sideline with his right arm in a sling. The severity of the injury likely won't be known until Monday.

See Qwixcore account of the game

Bosco (3-0) outscored the Arizona power 42-3 in the final two-plus quarters to score the victory at the the Mission Viejo Classic. Sophomore Sean McGrew put the finishing touches on this one with an 88-yard touchdown run in the fourth quarter.

"When I first got out there, I was a little nervous, but after that first series I calmed down, made the throws, made the reads," Katnik told the Los Angeles Times.

Chandler (2-1) raced to its big lead behind quarterback Bryce Perkins, who completed 26 of 38 for 250 yards and added 130 yards rushing, including a 63-yard touchdown to open the scoring. But Bosco eventually wore down Chandler.

Jaleel Wadood had nine catches for 125 yards and two touchdowns for the winners. Junior running back Manasseh Anesi gave Bosco its first touchdown on a 3-yard run midway through the third quarter to go up 31-28. Anesi added scoring runs of 1 and 25 yards down the stretch.

St. John Bosco coach Jason Negro said Katnik can run the team without a hitch if Rosen is out for an extended time.

"However long Josh is out, Andrew will be able to perform," he told the Los Angeles Times.

He sure got off to a good start on Saturday.