Indiana football's offensive line has been one of the few constants throughout a season filled with injuries, close calls and difficult decisions. That continuity will be tested Saturday.

Starting right guard Joe Brunner was a surprise addition to Thursday night's Big Ten availability report, listed as out for Indiana's matchup with USC. Brunner, who transferred from Wisconsin in January, has started all nine games this season and played a team-high 542 snaps along the offensive line.

According to CBS Sports' Matt Zenitz, Brunner suffered an injury during Thursday's practice. His absence means Indiana will have to make its first change to a starting offensive line that has remained intact through nine games.

Fortunately for Curt Cignetti, there are several ways to approach it. The question is whether Indiana prefers a straightforward replacement or a more significant reshuffling of its offensive line.

If Indiana wants to make a one-for-one substitution, Austin Leibfried appears to be the most logical candidate.

The redshirt sophomore has appeared in all nine games this season and 22 throughout his Indiana career, including two starts. He's also been a regular contributor in the Hoosiers' six offensive-lineman packages, giving him considerably more experience than most of Indiana's other reserves.

Leibfried has primarily played at center and left guard this season, but his versatility gives Indiana some flexibility.

One possibility would be inserting Leibfried at center and moving starting center Bray Lynch back to right guard, where he played last season. That would allow Indiana to lean on two players with starting experience rather than asking a less experienced reserve to handle Brunner's responsibilities.

Of course, there's something to be said for keeping the rest of the offensive line together. Leibfried could simply slide into Brunner's spot, allowing Indiana to maintain continuity at the other four positions.

Either way, Leibfried figures to be heavily involved in the conversation.

Leibfried isn't Indiana's only option, and Cignetti has consistently emphasized getting his best five offensive linemen on the field.

That philosophy could open the door for starting right tackle Adedamola Ajani to move inside.

Ajani spent time working at right guard during fall camp and has previous experience along the interior. If Indiana elects to move him inside, redshirt freshman Baylor Wilkin could step in at right tackle, where he's played 22 snaps this season.

It's an intriguing possibility, although it would require changing two positions rather than one. With USC coming to Bloomington for a top-20 matchup, disrupting an established combination carries some risk.

Indiana could also turn to true freshman Sam Simpson, who has played 23 snaps at right guard this season. Simpson has graded well in limited opportunities, but those snaps have largely come in games that were already decided. Asking him to start against USC would represent a significant jump in responsibility.

Matt Marek and Evan Parker have also seen limited action on the interior and provide additional depth.

The Hoosiers aren't short on candidates. What remains to be seen is how much Cignetti and his staff are willing to change to replace one starter.

Brunner wasn't the only notable name on Thursday's report.

Starting running back Turbo Richard remains out after suffering an injury against Minnesota. Richard leads Indiana with 745 rushing yards and six touchdowns, while defensive lineman Kellan Wyatt will miss his second consecutive game.

Linebacker Rolijah Hardy remains questionable after missing the Minnesota game with an injury sustained during pregame warmups. Cornerback A.J. Harris, meanwhile, was upgraded from questionable to probable.