"Scott Mruczkowski has a strained ankle at the minimum. It could be worse," said Coach Norv Turner.
There's a chance the man Mruczkowski was subbing for, Pro Bowler Nick Hardwick, will be able to play this week for the first time since the season-opener. Hardwick will practice this week and will play against the Titans unless he suffers a setback.
However, Hardwick tried practicing just two weeks ago and aggravated his ankle injury. Even if he's able to avoid a similar fate this time around, there's no guarantee he'll be able to finish the game a physical Tennessee defense.
C Dennis Norman
If Hardwick can't play, Norman would start and rookie Tyronne Green would be the backup.
"From training camp, I've probably had a handful of snaps with [Norman] in there," Philip Rivers said. "But Dennis is a solid, veteran player. It wasn't too big for him at all stepping in there."
Elsewhere on the offensive line, first-year tackle Brandyn Dombrowski had another strong showing against the Bengals and figures to hold onto his starting job ahead of veteran Jon Runyan for at least one more game.
On the defensive line, the injuries continue to mount. Jacques Cesaire injured his elbow versus the Bengals, and although he's optimistic about his availability for the Titans game, he's a player to watch throughout the course of this short week.
If Cesaire can't go, Alfonso Boone, who amazingly has only one fewer sack than Shawne Merriman (four to three), would get the start. This would force extended snaps on Travis Johnson, who is playing through a nagging groin injury.
Boone is also the backup nose tackle since the team placed Ogemdi Nwagbuo on IR a few weeks back with an ankle injury.
Starting nose tackle Ian Scott is earning his praise for his performance over the last month or so, but any time a team uses a No. 4 nose tackle (behind Jamal Williams, Ryon Bingham and Nwagbuo) against a player as explosive as the league's leading rusher, Tennessee's Chris Johnson, it's a scary proposition.
Can San Diego's lines hold up in Tennessee? Talk about it in the message boards.
Michael Lombardo is a member of the Pro Football Writers of America and a long-time contributor to the Scout.com network. His analysis has been published by the NFL Network, Fox Sports and MySpace Sports. He has followed the Chargers for more than 15 years and covered the team since 2003. You can see more of his updates by following him on twitter.