GLENDALE, Ariz. (AP) Arizona Cardinals first-round draft pick D.J. Humphries has a hyperextended right knee.

Humphries, the 24th pick overall out of Florida, slipped on the turf and limped off the field during Tuesday's practice. An MRI showed the injury was not severe. Coach Bruce Arians said Wednesday that the big offensive tackle could be out up to a week.

Humphries, trying to unseat Bobby Massie as starting right tackle, was one of 13 players sitting out Wednesday's practice with injuries.

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On Tuesday, Carson Palmer took a training camp day off when healthy for the first time in his NFL career, although he said he didn't like it.

''It was something that was set in stone months ago,'' the quarterback said Wednesday in his weekly meeting with reporters. ''It was something I argued with for probably six weeks and then just gave up because I realized I was getting nowhere with it.''

Palmer, 35, is coming off surgery to repair a torn ACL and he acknowledged the day off might have done him good.

''I think so,'' he said. ''I won't admit that to them but I understand what they're thinking.''

He said the plan is to have him take off every fourth or fifth day. On Wednesday, backup quarterback Drew Stanton had the day off. Stanton also is coming off a knee injury, although less severe than Palmer's.

Palmer took a tumble in Monday's practice, the first of the camp for the team in pads, but said it never fazed him.

''It looked a lot worse obviously than it was when I saw it on film,'' he said. ''I didn't really realize what happened, especially because we were in a two-minute drill, and you're focused on what happened on that play, and then what you're going to do on the next play, and really didn't think twice about it.''

Safety Tyrann Mathieu pushed running back Kerwynn Williams into Palmer's legs, knocking the quarterback over.

Palmer said Mathieu has checked on him a number of times since.

''He was more scared than I was,'' Palmer said, ''a little more nervous than I was when it happened.''

Mathieu said Tuesday that ''my heart was in my behind'' when Palmer went down.

New to the injured list, along with Humphries, were guard Earl Watford (knee), linebacker Darryl Sharpton (hip flexor), running back Marion Grice (hamstring) and tight end Ted Bolser (knee).

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