There was a scary moment toward the end of Thursday afternoon's training camp practice, when linebacker Deone Bucannon's left knee collided with wideout Brice Butler's helmet.

Bucannon stayed down for a few moments as a hush fell over University of Phoenix Stadium, but he seems to have avoided significant injury. Bucannon didn't practice on Friday but could be back relatively soon.

"He just hyperextended his knee," coach Steve Wilks said. "He's going to get an MRI (Friday), but I don't really expect him to miss a long period of time. We just wanted to be cautious (Friday) and not put him right back out there."

Bucannon wasn't present during the open portion of the morning practice, while cornerback Lou Young III, cornerback Jonathan Moxey and linebacker Airius Moore were working on the side. There have been scattered bumps and bruises in training camp, but the Cardinals have not dealt with a major injury to a core player, and Wilks is keeping his fingers crossed it remains that way.

"Any time one of your players go down, it's a scary feeling because regardless of who it is, you don't want to lose anybody," Wilks said. "We're doing some great things right now, but it's football and you've seen it throughout the league, unfortunately, the last couple of days with guys going down. Hopefully we can continue to stay healthy."

UPDATE: Later Friday, ESPN reported Bucannon's MRI indeed revealed no serious damage.