A player was blocked into Cooper's leg while the guard was running down the field trying to make a block midway through the third quarter. Cooper couldn't put any weight on the leg after the injury and had to be helped off the field.
The highly athletic guard, whom Arizona drafted No. 7 overall, was enjoying a nice training camp and was expected to spearhead an improved Cardinals offensive line.
Earlier in the night, Cardinals nose tackle Dan Williams left with an ankle injury. His return was listed as doubtful. Starting tight end Rob Housler also was knocked out with an ankle injury, and starting running back Rashard Mendenhall left with a knee injury, although his injury didn't look too serious.