Cardinals' Johnson carted to locker room with knee injury

A disappointing campaign for the Arizona Cardinals might have gotten worse in the regular-season finale Sunday.

Cardinals star running back David Johnson - who's been one of the few bright spots on the team - was carted to the locker room after suffering a left knee injury against the Los Angeles Rams.

Johnson was able to limp off the field and was immediately attended to by trainers on the sideline. He was then transported to the locker room. The Cardinals ruled him questionable to return.

The second-year back's left leg bent at an awkward angle as he was tackled.

(Warning: Video contains graphic content)

If Johnson's injury is serious, it could hamper the Cardinals' offseason attempt to craft a bounce-back campaign, since he's quickly established himself as the club's most invaluable player.