Kansas City Chiefs star running back Jamaal Charles headed to the locker room to be examined for a concussion and was later ruled out for the game.

His return was initially announced as questionable.

Charles had rushed for 18 yards on his first three carries of the Chiefs' wild-card playoff game against the Indianapolis Colts at Lucas Oil Stadium.

Charles appeared to land on his head and was being tested under the NFL concussion testing protocol on the sideline before heading inside with a team doctor.

Knile Davis is filling in for Charles and playing well so far.

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Aaron Wilson covers the Ravens for The Baltimore Sun.