Kansas City Chiefs wide receiver Freddie Mitchell inured his knee in Sunday?s morning special-teams workout. Vermeil said the injury ?doesn?t appear to be a serious one,? but it?s obviously a blow to Mitchell, the former Philadelphia Eagle who?s fighting for a spot on the roster. Mitchell, who signed as a free agent in June, had impressed the Chiefs coaches through the first three days of camp with his work ethic and ability to make several difficult catches. Mitchell may leave the camp to have his knee scoped to measure the extent of the damage.