The San Francisco 49ers' resounding 35-11 victory over the St. Louis Rams on "Thursday Night Football" came with a potentially serious cost.

On what proved to be the 49ers' last offensive snap of the night left tackle Joe Staley appeared to injure his knee. His loud screams were picked up by the television cameras while players and coaches from both teams came out to offer support.

Staley eventually was helped up and taken to the locker room by two 49ers staffers. San Francisco already came into the game banged up with linebacker Patrick Willis and cornerback Nnamdi Asomugha out of the lineup. Linebacker Aldon Smith also is away from the team indefinitely while he addresses his substance-abuse problem.