The Southern Cal  game turned out to be even more painful for the Huskers than first imagined.

Nebraska coach Bill Callahan said Monday that junior left guard Andy Christensen suffered a knee injury that will keep him out the remainder of the season.

“He’s the only player at this point that will be ruled out of the Ball State game,” Callahan said during the Big 12 Coaches Teleconference.

Christensen, a 6-foot-3, 305-pound junior from Bennington, injured himself while blocking downfield in the first quarter of the 49-31 loss to USC.

Callahan was not specific when asked about the type of knee injury suffered.

Christensen worked his way up from the scout team and battled through a 2005 shoulder injury that required surgery to start eight games last year as a sophomore.

He played in all 14 games, busting into the starting lineup in mid-season while teammate Greg Austin struggled with knee injuries.

After Christensen’s injury Saturday, junior Mike Huff got the majority of snaps in his place.

It’s suspected Huff will start at left guard against Ball State.

Callahan was also quizzed on the health of senior cornerback Zack Bowman, who injured a hamstring while covering a long sideline route in the second quarter.

Bowman did not return to the game.

To the question of if Bowman was OK, Callahan said: “As far as I know, yeah.”

Callahan was few on words when it came to talking about the USC game and what weaknesses were revealed after watching the game film.

“Basically, fundamentals. That’s the one area that we addressed, fundamentals,” Callahan said. “Just total fundamentals, the function of defensive football, just the fundamental position of defensive football.”

He said coaches and players looked at the tape, established an honest assessment of where they’re at, and have already moved on.

“We’re focusing on Ball State right now,” Callahan said. “That’s where our focus is at.”

Reach Brian Christopherson at 473-7439 or bchristopherson@journalstar.com.