USC’s 36-27 loss to No. 6 Oregon on Saturday in Autzen Stadium eliminated the Trojans from Pac-12 championship contention. Quarterback Caleb Williams threw for 291 yards and one touchdown on 19-of-34 passing, but Oregon’s Bo Nix stole the show with 412 yards and four touchdowns.

The Trojans (7-4, 5-3 Pac-12) have dropped four of their last five games and have only bragging rights to play for in their regular-season finale at the Coliseum next Saturday against rival UCLA.

A rivalry game with such low stakes felt like a nightmare scenario just five weeks ago. USC was 6-0 and still in the College Football Playoff conversation. But it was all a far-flung dream.

The back-loaded schedule exposed USC’s defensive flaws to the point that Riley had no choice but to fire defensive coordinator Alex Grinch this week. Even after getting embarrassed by Washington, the Trojans still had plenty to play for, Riley emphasized.

Yet the dramatic midseason coaching change did little to change the results on the field. Nix threw 77- and 84-yard touchdowns on his first two passes. The Ducks scored two touchdowns in five combined plays. It felt like USC was destined for a blowout loss.

Williams wasn’t going to make it that easy.

Oregon wide receiver Tez Johnson, right, avoids USC cornerback Domani Jackson after making a catch in the first half Saturday.

(Andy Nelson / Associated Press)

The reigning Heisman Trophy winner willed the Trojans to an eight-point halftime deficit that felt like a minor victory in front of a packed Autzen Stadium and an Oregon team that has emerged as the Pac-12’s strongest since losing to rival Washington on Oct. 14. He slung a 10-yard pass to Austin Jones over his head like a hook shot. He scrambled for eight yards on a critical third-and-five in the red zone to set up a five-yard, game-tying touchdown from MarShawn Lloyd in the first quarter. He kept the Trojans within one possession with a two-yard touchdown run with 12 seconds remaining in the first half.

Oregon’s self-inflicted mistakes let USC stay close. The Ducks committed 13 penalties for 120 yards and missed a field goal with 6:27 to go in the fourth. The Trojans responded with a 13-yard touchdown run by Jones with 3:44 remaining, but failed to convert on a two-point try to pull within one possession.

Oregon recovered USC’s onside kick and converted a fourth down to ice the game as Nix found running back Bucky Irving wide open in the flat for a nine-yard gain.