Mario Williams dressed for USC Football and was on the sideline for the entire game at Arizona, but randomly didn't play. It was random as he was not even on the radar to potentially miss time leading up to the game, and it was a complete mystery as to why he wasn't playing. With Lincoln Riley typically liking to keep things internal as far as injuries go, nobody knew what was going on.
Turns out, Williams actually was indeed dealing with an ailment, and he had a "tweak come up" in pre-game, according to Lincoln Riley:
So, not only did everyone watching the game expect him to play, but even the team expected him to play. It clearly was not expected to be a key injury at all. It's also interesting, because in the game prior to this one, Williams had four catches for 145 receiving yards.
Therefore, if he originally suffered this injury (prior to the tweak, of course) during the last game, he was outstanding while playing through it against Utah. While Riley is obviously not specifying what the injury was, it can't be too bad if he dressed and was supposed to play on Saturday, and also played out of his mind in the last game.
Luckily, USC Football's other wide receivers stepped up without Mario Williams in the game.
Remember, it wasn't just Mario Williams who wasn't playing in the game for the USC Football Wide Receiver room, but also Jordan Addison. Both Tahj Washington and Kyle Ford balled out of control. Washington grabbed seven footballs for 118 receiving yards and two receiving scores. Ford had six catches for 114 yards. Brenden Rice even chipped in 62 receiving yards on five catches and a score.
The 'Next Man Up' philosophy was clearly out in full force for this crop of receivers. Even Michael Jackson III had 72 all-purpose yards. The wide receivers gained 435 all-purpose yards (382 receiving) on the day without their top two players at the position. Riley will most certainly take that, as he now knows what his group is made of even without his best guys.