A USC offense with big expectations has suffered a tough blow just weeks before the season-opener against San Jose State on Aug. 29. Starting center Kilian O’Connor suffered a season-ending knee injury in practice on Wednesday, Lincoln Riley announced.

Riley described the incident as a “non-contact kind of freak injury” and confirmed that O’Connor won’t take the field in 2026. The Trojans coach said it was a tough pill to swallow given O’Connor’s journey from walk-on to starting center.

“Tough one for us I think more than anything from just an emotional standpoint,” Riley said, per 247Sports. “Tremendous leader. Obviously well-versed on his track here as a walk-on into becoming a team leader and one of the heartbeats of this program.”

The Rimington Trophy, which is handed out to the best center in the nation, had earlier in the day announced O’Connor as on the watch list for the award. 

O’Connor was a walk-on in the 2022 signing class, but he persevered and started in the Las Vegas Bowl at the end of the 2024 season. Last season, O’Connor beat out Syracuse transfer J’Onre Reed to earn the starting job out of camp and started the first five games of the season before injuries derailed him.

Coming into camp, there was a chance that USC could roll out the same starting offensive line as last season, but that’s no longer the case. When it comes to replacing O’Connor, the Trojans do have a couple of options at their disposal.

This early injury will certainly test the team’s depth in the trenches. According to 247Sports, guard Tobias Raymond could slide over and assume center duties as a more experienced play. However, redshirt freshman Willi Wascher and true freshman Kannon Smith — both three-star recruits out of high school — are candidates to fill that role as well.

With O’Connor and others in and out of the lineup last season, the offensive line deployed seven different starting units. Even still, it did a great job of keeping star quarterback Jayden Maiava upright. The Trojans allowed just 1.15 sacks per game, which ranked 14th in the country. In the running game, the line paved the way for a 169.5 yards per game and 5.15 yards per carry.

No matter what happens at the center position, USC should be very good at the other four spots. That’s especially true at tackle, where Elijah Page returns to man the left side, and Justin Tauanuu is back to assume his post on the right.

The Trojans debuted at No. 14 in the preseason USA Today Coaches Poll earlier this week.