Chargers center Ohrnberger misses practice, listed as doubtful for Sunday

Chargers center Rich Ohrnberger didn't practice Friday because of a sore back.

Ohrnberger has replaced San Diego center Nick Hardwick, after the Pro Bowler suffered a season-ending neck injury on Sept. 8.

So Ohrnberger's availability when the Chargers host the Jacksonville Jaguars on Sunday is crucial.

If Ohrnberger, who is listed as doubtful, can't go, rookie Chris Watt is his likely replacement.

Watt is a third-round pick out of Notre Dame. He had a spirited camp battle with Johnnie Troutman at right guard, but Watt also took snaps at center.